The t-PA –7351C>T polymorphism affects enhancer responsiveness to retinoic acid. HeLa cells were transiently transfected with either the t-PA950(–7351C)-Luc or t-PA950(–7351T)-Luc construct, cotransfected with a Renilla luciferase–expressing vector, and stimulated with 5 different concentrations of RA for 24 hours. Fold increase represents the normalized increase in activity in the indicated construct relative to empty vector (pGL3-promoter vector lacking enhancer insert). As RA was dissolved in DMSO, cells were also exposed to DMSO alone as control. Results are presented as mean (n = 9) and SEM. ANOVA main effect of genotype P < .001, genotype × treatment interaction P < .01. Post hoc analysis by t test; NS indicates not significant, **P < .01, ***P < .001.