Mediator subunits differentially affect AR transcriptional activity and prostate cancer cell proliferation. (A) LNCaP cells stably expressing an AR-responsive probasin-luciferase reporter gene were transfected with siRNAs against the indicated Mediator complex subunits or a scrambled, nonsilencing siRNA (control) and, after 48 h, were treated with 10 nM R1881 for 24 h. Luciferase activity was measured and normalized to protein and presented as relative luminescence units (RLUs). (B) The efficiency of knockdown of each factor was determined at the mRNA level relative to RPL19 and shown as relative mRNA expression. (White bars) Nonsilencing siRNA; (black bars) the indicated siRNAs. (C) LNCaP-abl cells were transfected with siRNAs against the indicated Mediator complex subunits or a scrambled, nonsilencing siRNA (control), and cell proliferation was measured after 7 d as in Figure 1. Data are shown as relative fluorescence units (RFUs). (D) Efficiency of knockdown at the mRNA level is shown relative to RPL19. (White bars) Nonsilencing siRNA; (black bars) the indicated siRNAs. Each assay was performed in triplicate, with error bars representing the standard deviation.