RB deletion causes impairment of Sertoli cell cycle quiescence. A, Venn diagram of microarray changes in E2F-related, cell cycle-regulatory, and DNA synthesis genes shows the overlap between these pathways. B, Quantitative RT-PCR of select (bold) genes from panel A, and E2f1 confirms the up-regulation of these genes in Rb cKO Sertoli cells (*, P < 0.05; **, P < 0.01; control, n = 6; Rb cKO, n = 5). RQ, Relative quantification. C–F, Immunofluorescent analysis of BrdU (red) and Sox9-GFP (green) indicates that occasional 6-wk-old Rb cKO Sertoli cells show persistent DNA synthesis (S phase). Arrows (C) indicate Sertoli cells that were not BrdU positive.