Publications by authors named "Joel E Martinez"

17 Publications

  • Page 1 of 1

Bridging the serodivide: attitudes of PrEP users towards sex partners living with HIV.

AIDS Care 2021 Jul 19:1-4. Epub 2021 Jul 19.

Department of Work & Social Psychology, Maastricht University, Maastricht, the Netherlands.

The introduction of biomedical HIV prevention methods, such as pre-exposure prophylaxis (PrEP), holds the potential to overcome the serodivide. We investigated the attitudes of PrEP users towards having sex with partners living with HIV. PrEP users in the Netherlands were recruited online and completed three questionnaires over a period of six months. We investigated changes over time in feelings of fear of HIV, comfort, and attitudes towards condom use when having sex with men living with HIV (MLHIV). A majority of PrEP users in our sample (up to 71.6%) had sex with MLHIV. Feeling comfortable to have sex with MLHIV did not change over time, but was already at a high level at T1. Most importantly, feeling safe not to use condoms with HIV-positive partners significantly increased, and did so in a rather short period of time after the onset of PrEP use (3-6 months). Taken together, the findings suggest that that PrEP may contribute to decreasing the serodivide between MSM rather quickly after the onset of PrEP use.
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http://dx.doi.org/10.1080/09540121.2021.1954588DOI Listing
July 2021

Quality of Sex Life and Perceived Sexual Pleasure of PrEP Users in the Netherlands.

J Sex Res 2021 Jun 15:1-6. Epub 2021 Jun 15.

Department of Work & Social Psychology, Maastricht University.

Next to its benefits for HIV prevention, PrEP may have psychosocial benefits relating to improved quality of sex life. The aim of the current study was to investigate the onset of changes in the quality of sex life and sexual pleasure of PrEP users in the first months of commencing PrEP use. Moreover, we investigated what factors were related to the quality of sex life of PrEP users. We recruited 145 participants via the Dutch PrEP-advocacy website PrEPnu.nl, and they received follow-up questionnaires after three and six months. We found that PrEP users reported an increase in the quality of their sex life, which was related to reduced fear of HIV since they started using PrEP but not to decreased condom use. PrEP users were more interested in experimenting with sex practices, but they did not always feel more desirable as a sex partner because of PrEP use. Health-care providers and health promotion campaigns could emphasize the positive effects of PrEP on the quality of sex life, in addition to the HIV-preventive effects of PrEP, to decrease PrEP stigma and increase PrEP uptake.
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http://dx.doi.org/10.1080/00224499.2021.1931653DOI Listing
June 2021

Slow Uptake of PrEP: Behavioral Predictors and the Influence of Price on PrEP Uptake Among MSM with a High Interest in PrEP.

AIDS Behav 2021 Aug 21;25(8):2382-2390. Epub 2021 Feb 21.

Department of Work & Social Psychology, Faculty of Psychology and Neuroscience, Maastricht University, PO Box 616, 6200 MD, Maastricht, The Netherlands.

Despite the improved availability and affordability of PrEP in the Netherlands, PrEP uptake is low among men who have sex with men (MSM). To optimize uptake, it is important to identify facilitators and barriers of PrEP use. During our study period, the price of PrEP dropped significantly after generic PrEP was introduced. We investigated whether the price drop predicts PrEP uptake, alongside behavioral and demographic characteristics. Participants (N = 349) were recruited online and completed three questionnaires over a period of 6 months, between February 2017 and March 2019. After 6 months, 159 (45.6%) participants were using PrEP. PrEP uptake was greater among MSM who ever had postexposure prophylaxis (PEP) treatment, among MSM with a better perceived financial situation, and when the price of PrEP dropped. MSM in a tighter perceived financial situation may use PrEP more when it would be free or fully reimbursed.
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http://dx.doi.org/10.1007/s10461-021-03200-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8222036PMC
August 2021

Narratives Shape Cognitive Representations of Immigrants and Immigration-Policy Preferences.

Psychol Sci 2021 02 13;32(2):135-152. Epub 2021 Jan 13.

Department of Psychology, Harvard University.

Scholars from across the social and media sciences have issued a clarion call to address a recent resurgence in criminalized characterizations of immigrants. Do these characterizations meaningfully impact individuals' beliefs about immigrants and immigration? Across two online convenience samples (total = 1,054 adult U.S. residents), we applied a novel analytic technique to test how different narratives-achievement, criminal, and struggle-oriented-impacted cognitive representations of German, Russian, Syrian, and Mexican immigrants and the concept of immigrants in general. All stories featured male targets. Achievement stories homogenized individual immigrant representations, whereas both criminal and struggle-oriented stories racialized them along a White/non-White axis: Germany clustered with Russia, and Syria clustered with Mexico. However, criminal stories were unique in making our most egalitarian participants' representations as differentiated as our least egalitarian participants'. Narratives about individual immigrants also generalized to update representations of nationality groups. Most important, narrative-induced representations correlated with immigration-policy preferences: Achievement narratives and corresponding homogenized representations promoted preferences for less restriction, and criminal narratives promoted preferences for more.
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http://dx.doi.org/10.1177/0956797620963610DOI Listing
February 2021

Socio-Sexual Experiences and Access to Healthcare Among Informal PrEP Users in the Netherlands.

AIDS Behav 2021 Apr 16;25(4):1236-1246. Epub 2020 Nov 16.

Department of Work & Social Psychology, Maastricht University, PO Box 616, 6200 MD, Maastricht, the Netherlands.

The aim of this qualitative study was to explore the experiences of informal PrEP users regarding access to PrEP and PrEP-related healthcare, community responses, sexual behavior and well-being. We interviewed 30 men who have sex with men (MSM) in semi-structured online interviews between March and August 2018. Interviews were analyzed using interpretive description. Informal PrEP users were well informed about the use of PrEP, but sometimes did not make use of renal testing. Participants reported a lack of PrEP knowledge among healthcare providers, which limited their access to PrEP and put them at risk, as they received incorrect information. Although some participants reported negative reactions from potential sex partners, most received positive reactions and were sometimes seen as more desirable sex partners. PrEP healthcare services should not only be accessible to formal PrEP users, but also to PrEP users who procure PrEP informally.
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http://dx.doi.org/10.1007/s10461-020-03085-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7973587PMC
April 2021

Quantifying idiosyncratic and shared contributions to judgment.

Behav Res Methods 2020 08;52(4):1428-1444

Department of Psychology, Princeton University, Princeton, NJ, USA.

Identifying relative idiosyncratic and shared contributions to judgments is a fundamental challenge to the study of human behavior, yet there is no established method for estimating these contributions. Using edge cases of stimuli varying in intrarater reliability and interrater agreement-faces (high on both), objects (high on the former, low on the latter), and complex patterns (low on both)-we showed that variance component analyses (VCAs) accurately captured the psychometric properties of the data (Study 1). Simulations showed that the VCA generalizes to any arbitrary continuous rating and that both sample and stimulus set size affect estimate precision (Study 2). Generally, a minimum of 60 raters and 30 stimuli provided reasonable estimates within our simulations. Furthermore, VCA estimates stabilized given more than two repeated measures, consistent with the finding that both intrarater reliability and interrater agreement increased nonlinearly with repeated measures (Study 3). The VCA provides a rigorous examination of where variance lies in data, can be implemented using mixed models with crossed random effects, and is general enough to be useful in any judgment domain in which agreement and disagreement are important to quantify and in which multiple raters independently rate multiple stimuli.
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http://dx.doi.org/10.3758/s13428-019-01323-0DOI Listing
August 2020

Pre-exposure prophylaxis sorting among men who have sex with men.

AIDS Care 2019 03 9;31(3):388-396. Epub 2018 Oct 9.

b Department of Work and Social Psychology , Maastricht University , Maastricht , The Netherlands.

Factors such as race, masculinity, and sexually transmitted infections have been documented to influence partner selection in men who have sex with men (MSM). Pre-exposure prophylaxis (PrEP) has received mixed evaluations as a responsible step in HIV prevention and as an enabler of risker sexual practices. PrEP may consequently serve as an additional factor in partner choice. We examine the role that PrEP use and "promiscuity" play in affiliation and dating decisions by men who have sex with men with different HIV and PrEP stati. We invited 450 MSM across the United States from a smartphone geo-locating sex application to complete a survey of which 339 successfully finished the task. The survey contained vignettes of fictional men who were promiscuous or monogamous and either taking PrEP or not. Participants provided responses on whether to affiliate with these characters in three social domains: as friends, dates, or sex partners. Neither PrEP nor promiscuity influenced friendship choices. There was a preference for dating monogamous characters. Critically, PrEP influenced sexual affiliations for HIV negative individuals who showed a preference for PrEP-using characters. The pattern of results provides quantitative evidence for PrEP-based sexual sorting aimed at reducing risk of HIV transmission.
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http://dx.doi.org/10.1080/09540121.2018.1533229DOI Listing
March 2019

Control Engagement During Sentence and Inhibition fMRI Tasks in Children With Reading Difficulties.

Cereb Cortex 2018 10;28(10):3697-3710

Department of Psychology, The University of Texas at Austin, Austin, TX, USA.

Recent reading research implicates executive control regions as sites of difference in struggling readers. However, as studies often employ only reading or language tasks, the extent of deviation in control engagement in children with reading difficulties is not known. The current study investigated activation in reading and executive control brain regions during both a sentence comprehension task and a nonlexical inhibitory control task in third-fifth grade children with and without reading difficulties. We employed both categorical (group-based) and individual difference approaches to relate reading ability to brain activity. During sentence comprehension, struggling readers had less activation in the left posterior temporal cortex, previously implicated in language, semantic, and reading research. Greater negative activity (relative to fixation) during sentence comprehension in a left inferior parietal region from the executive control literature correlated with poorer reading ability. Greater comprehension scores were associated with less dorsal anterior cingulate activity during the sentence comprehension task. Unlike the sentence task, there were no significant differences between struggling and nonstruggling readers for the nonlexical inhibitory control task. Thus, differences in executive control engagement were largely specific to reading, rather than a general control deficit across tasks in children with reading difficulties, informing future intervention research.
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http://dx.doi.org/10.1093/cercor/bhy170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6132278PMC
October 2018

Perceptual biases during cued task switching relate to decision process differences between children and adults.

J Exp Psychol Hum Percept Perform 2018 Oct 19;44(10):1603-1618. Epub 2018 Jul 19.

Department of Psychology.

Previous work suggests that children engage preparatory processing differently than adults in cued task switching. One potential consequence is that they are differentially biased by visual properties of the stimuli, for example, target-choice similarity. We tested this possibility in 215 children and young adults ranging from 6 to 27 years of age. Participants played a cue-target game with varying levels of working memory and attentional demand where they matched multidimensional stimuli according to a cued dimension. Younger age, low working memory demand, and matching fine grained dimensions (i.e., pattern) increased the bias of target-choice similarity on task performance. Older age, high working memory, and matching global dimensions (i.e., shape) mitigated the bias. Developmental transitions to adult performance differed by task demands but generally occurred during adolescence. A drift diffusion analysis revealed age and task differences in decision making strategies consistent with how similarity impacted task performance, indicating that, especially with low working memory demand, children made impulsive, similarity-driven decisions. Our findings support the idea that children engage in preparation strategies that exacerbate perceptual biases on task performance; improvements are observed with age or through changes in task structure and stimuli. These results have implications for interpreting cognitive control performance in children. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
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http://dx.doi.org/10.1037/xhp0000552DOI Listing
October 2018

Robust effects of affective person learning on evaluation of faces.

J Pers Soc Psychol 2018 Apr;114(4):516-528

Department of Psychology, Princeton University.

People form impressions of others from multiple sources of information. Facial appearance is one such source and judgments based on facial appearance are made after minimal exposure to faces. A more reliable source of information is affective person learning based on others' past actions. Here we investigated whether the effects of such appearance-independent learning on face evaluation emerge after rapid face exposure, a response deadline procedure, and a lack of explicit recognition of the faces. In three experiments, participants learned to associate novel faces with negative and positive behaviors, and then evaluated the faces presented on their own, without the behaviors. Even after extremely brief exposures (e.g., 35 ms), participants evaluated faces previously associated with negative behaviors more negatively than those associated with positive behaviors (Experiment 1). The learning effect persisted when participants were asked to evaluate briefly presented faces before a response deadline (Experiment 2), although the effect was diminished. Finally, although this learning effect increased as a function of face recognition (Experiment 3), it was present with only minimal recognition, suggesting that participants do not need to deliberately retrieve behavioral information for it to influence face evaluation. Together, the findings suggest that person learning unrelated to facial appearance is a powerful determinant of face evaluation. (PsycINFO Database Record
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http://dx.doi.org/10.1037/pspa0000109DOI Listing
April 2018

A pragmatist philosophy of psychological science and its implications for replication.

Behav Brain Sci 2018 01;41:e127

Department of Psychology,Princeton University,Princeton, NJ

A pragmatist philosophy of psychological science offers to the direct replication debate concrete recommendations and novel benefits that are not discussed in Zwaan et al. This philosophy guides our work as field experimentalists interested in behavioral measurement. Furthermore, all psychologists can relate to its ultimate aim set out by William James: to study mental processes that provide explanations for why people behave as they do in the world.
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http://dx.doi.org/10.1017/S0140525X18000626DOI Listing
January 2018

Consistent Performance Differences between Children and Adults Despite Manipulation of Cue-Target Variables.

Front Psychol 2017 3;8:1304. Epub 2017 Aug 3.

Department of Psychology, The University of Texas at Austin, AustinTX, United States.

Two behavioral experiments assessed the plasticity and short-term improvement of task switching in 215 children and adults. Specifically, we studied manipulations of cued attention to different features of a target stimulus as a way to assess the development of cognitive flexibility. Each experiment had multiple levels of difficulty via manipulation of number of cued features (2-4) and number of response options (2 or 4). Working memory demand was manipulated across the two experiments. Impact of memory demand and task level manipulations on task accuracy and response times were measured. There were three overall goals: First, these task manipulations (number of cued features, response choices, and working memory load) were tested to assess the stability of group differences in performance between children ages 6-16 years and adults 18-27 years, with the goal of reducing age group differences. Second, age-related transitions to adult-level performance were examined within subgroups of the child sample. Third, short-term improvement from the beginning to the end of the study session was measured to probe whether children can improve with task experience. Attempts to use task manipulations to reduce age differences in cued task switching performance were unsuccessful: children performed consistently worse and were more susceptible to task manipulations than adults. However, across both studies, adult-like performance was observed around mid-adolescence, by ages 13-16 years. Certain task manipulations, especially increasing number of response options when working memory demand was low, produced differences from adults even in the oldest children. Interestingly, there was similar performance improvement with practice for both child and adult groups. The higher memory demand version of the task (Experiment 2) prompted greater short-term improvement in accuracy and response times than the lower memory demand version (Experiment 1). These results reveal stable differences in cued switching performance over development, but also relative flexibility within a given individual over time.
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http://dx.doi.org/10.3389/fpsyg.2017.01304DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5541061PMC
August 2017

Knowledge of Social Affiliations Biases Economic Decisions.

PLoS One 2016 21;11(7):e0159918. Epub 2016 Jul 21.

Department of Psychology, The University of Texas at Austin, Austin, TX, United States of America.

An individual's reputation and group membership can produce automatic judgments and behaviors toward that individual. Whether an individual's social reputation impacts interactions with affiliates has yet to be demonstrated. We tested the hypothesis that during initial encounters with others, existing knowledge of their social network guides behavior toward them. Participants learned reputations (cooperate, defect, or equal mix) for virtual players through an iterated economic game (EG). Then, participants learned one novel friend for each player. The critical question was how participants treated the friends in a single-shot EG after the friend-learning phase. Participants tended to cooperate with friends of cooperators and defect on friends of defectors, indicative of a decision making bias based on memory for social affiliations. Interestingly, participants' explicit predictions of the friends' future behavior showed no such bias. Moreover, the bias to defect on friends of defectors was enhanced when affiliations were learned in a social context; participants who learned to associate novel faces with player faces during reinforcement learning did not show reputation-based bias for associates of defectors during single-shot EG. These data indicate that when faced with risky social decisions, memories of social connections influence behavior implicitly.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0159918PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4956271PMC
July 2017

Inhibition of mammary tumor growth and metastases to bone and liver by dietary grape polyphenols.

Clin Exp Metastasis 2009 18;26(6):505-16. Epub 2009 Mar 18.

Department of Biochemistry, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR, USA.

The cancer preventive properties of grape products such as red wine have been attributed to polyphenols enriched in red wine. However, much of the studies on cancer preventive mechanisms of grape polyphenols have been conducted with individual compounds at concentrations too high to be achieved via dietary consumption. We recently reported that combined grape polyphenols at physiologically relevant concentrations are more effective than individual compounds at inhibition of ERalpha(-), ERbeta(+) MDA-MB-231 breast cancer cell proliferation, cell cycle progression, and primary mammary tumor growth (Schlachterman et al., Transl Oncol 1:19-27, 2008). Herein, we show that combined grape polyphenols induce apoptosis and are more effective than individual resveratrol, quercetin, or catechin at inhibition of cell proliferation, cell cycle progression, and cell migration in the highly metastatic ER (-) MDA-MB-435 cell line. The combined effect of dietary grape polyphenols (5 mg/kg each resveratrol, quercetin, and catechin) was tested on progression of mammary tumors in nude mice created from green fluorescent protein-tagged MDA-MB-435 bone metastatic variant. Fluorescence image analysis of primary tumor growth demonstrated a statistically significant decrease in tumor area by dietary grape polyphenols. Molecular analysis of excised tumors demonstrated that reduced mammary tumor growth may be due to upregulation of FOXO1 (forkhead box O1) and NFKBIA (IkappaBalpha), thus activating apoptosis and potentially inhibiting NfkappaB (nuclear factor kappaB) activity. Image analysis of distant organs for metastases demonstrated that grape polyphenols reduced metastasis especially to liver and bone. Overall, these results indicate that combined dietary grape polyphenols are effective at inhibition of mammary tumor growth and site-specific metastasis.
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http://dx.doi.org/10.1007/s10585-009-9250-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2898569PMC
August 2009

On the use of in vivo cargo velocity as a biophysical marker.

Biochem Biophys Res Commun 2007 Feb 22;353(3):835-40. Epub 2006 Dec 22.

Department of Biomedical Engineering, 204 Rockwell Engineering Center, Irvine, CA 92697-2715, USA.

Molecular motors move many intracellular cargos along microtubules. Recently, it has been hypothesized that in vivo cargo velocity can be used to determine the number of engaged motors. We use theoretical and experimental approaches to investigate these assertions, and find that this hypothesis is inconsistent with previously described motor behavior, surveyed and re-analyzed in this paper. Studying lipid droplet motion in Drosophila embryos, we compare transport in a mutant, Delta(halo), with that in wild-type embryos. The minus-end moving cargos in the mutant appear to be driven by more motors (based on in vivo stall force observations). Periods of minus-end motion are indeed longer than in wild-type embryos but the corresponding velocities are not higher. We conclude that velocity is not a definitive read-out of the number of motors propelling a cargo.
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http://dx.doi.org/10.1016/j.bbrc.2006.12.120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2889695PMC
February 2007

Gene expression changes induced in the testis by transplacental exposure to high and low doses of 17{alpha}-ethynyl estradiol, genistein, or bisphenol A.

Toxicol Sci 2005 Aug 18;86(2):396-416. Epub 2005 May 18.

Miami Valley Innovation Center, The Procter and Gamble Company, Cincinnati, Ohio 45253, USA.

The purpose of this study was to determine (1) the transcriptional program elicited by exposure to three estrogen receptor (ER) agonists: 17 alpha-ethynyl estradiol (EE), genistein (Ges), and bisphenol A (BPA) during fetal development of the rat testis and epididymis; and (2) whether very low dosages of estrogens (evaluated over five orders of magnitude of dosage) produce unexpected changes in gene expression (i.e., a non-monotonic dose-response curve). In three independently conducted experiments, Sprague-Dawley rats were dosed (sc) with 0.001-10 microg EE/kg/day, 0.001-100 mg Ges/kg/day, or 0.002-400 mg BPA/kg/day. While morphological changes in the developing reproductive system were not observed, the gene expression profile of target tissues were modified in a dose-responsive manner. Independent dose-response analyses of the three studies identified 59 genes that are significantly modified by EE, 23 genes by Ges, and 15 genes by BPA (out of 8740), by at least 1.5 fold (up- or down-regulated). Even more genes were observed to be significantly changed when only the high dose is compared with all lower doses: 141, 46, and 67 genes, respectively. Global analyses aimed at detecting genes consistently modified by all of the chemicals identified 50 genes whose expression changed in the same direction across the three chemicals. The dose-response curve for gene expression changes was monotonic for each chemical, with both the number of genes significantly changed and the magnitude of change, for each gene, decreasing with decreasing dose. Using the available annotation of the gene expression changes induced by ER-agonist, our data suggest that a variety of cellular pathways are affected by estrogen exposure. These results indicate that gene expression data are diagnostic of mode of action and, if they are evaluated in the context of traditional toxicological end-points, can be used to elucidate dose-response characteristics.
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http://dx.doi.org/10.1093/toxsci/kfi198DOI Listing
August 2005

A determinant for directionality of organelle transport in Drosophila embryos.

Curr Biol 2003 Sep;13(19):1660-8

Department of Developmental and Cell Biology, 2222 Natural Sciences I, University of California-Irvine, Irvine, CA 92697, USA.

Background: Motor-driven transport along microtubules is a primary cellular mechanism for moving and positioning organelles. Many cargoes move bidirectionally by using both minus and plus end-directed motors. How such cargoes undergo controlled net transport is unresolved.

Results: Using a combination of genetics, molecular biology, and biophysics, we have identified Halo, a novel regulator of lipid droplet transport in early Drosophila embryos. In embryos lacking Halo, net transport of lipid droplets, but not that of other cargoes, is specifically altered; net transport is minus-end directed at developmental stages when it is normally plus-end directed. This reversal is due to an altered balance of motion at the level of individual organelles; without Halo, travel distances and stall forces are reduced for plus-end and increased for minus-end motion. During development, halo mRNA is highly upregulated just as net plus-end transport is initiated (phase II), and its levels drop precipitously shortly before transport becomes minus-end directed (phase III). Exogenously provided Halo prevents the switch to net minus-end transport in phase III in wild-type embryos and induces net plus-end transport during phase II in halo mutant embryos. This mechanism of regulation is likely to be of general importance because the Drosophila genome encodes a family of related proteins with similar sequences, each transiently expressed in distinct domains.

Conclusions: We conclude that Halo acts as a directionality determinant for embryonic droplet transport and is the first member of a new class of transport regulators.
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http://dx.doi.org/10.1016/j.cub.2003.08.032DOI Listing
September 2003
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