Selenium-regulated gene expression. Relative steady state levels (mean ± SEM) of mRNA in the dorsolateral prostates of rats fed diets providing 10 or 600 mg/kg isoflavones, and 0 or 3.0 mg/kg supplemental Se for 200 days, were determined by real time RT-PCR of total RNA. Analysis of variance was used to determine significance of the main effects of isoflavones and supplemental Se. Fisher's pairwise comparisons within the ANOVA were used to test differences between pairs of dietary groups. Bars not sharing a common superscript are significantly different (p < 0.05) by Fisher's pairwise comparisons. Values are expressed relative to the expression level of the 0 Se supplement-10 mg/kg isoflavone group. A. Androgen receptor gene expression. For the androgen receptor (AR) the main effect of supplemental Se was highly significant (p < 0.001) while the main effect of isoflavones was not (p = 0.253). B. Dhcr 24 gene expression. For Dhcr24 the reduction in gene expression due to high Se intake was statistically significant (p < 0.001) while the effect of isoflavones was not (p = 0.438). C. Abcc gene expression. For Abcc4 (Mrp4) the main effect of high supplemental Se intake in reducing gene expression was statistically significant (p = 0.025) while the reduction due to high isoflavone intake was not (p = 0.055).