MED19 depletion affects AR target genes expression. MED19 knockdown decreases the expression of AR target genes in LNCaP (A) and LNCaP-abl (B) cells. Cells were transfected with control (siControl) or MED19 siRNA (siMED19), and either androgen deprived for 48 h and then treated with 10 nM R1881 for 24 h (LNCaP) or cultured in media with 10% charcoal-stripped FBS for 48 h (LNCaP-abl). Relative mRNA levels of the indicated genes were analyzed by qPCR and normalized to RPL19. Each assay was performed in duplicate, with error bars representing the range of the mean. (C–F) MED19 selectively regulates AR transcriptional activity. LNCaP-abl cells were transfected with control siRNA (siControl) or siRNA against MED19 (siMED19) together with (C) a plasmid expressing the Gal4 DNA-binding domain fused to the VP16 activation domain, along with a luciferase reporter gene driven by five Gal4-binding sites upstream of the E1b promoter. (D) A plasmid containing the human GR and a GR-responsive luciferase reporter, treated with 100 nM dexamethasone. (E) An AR-responsive luciferase reporter treated with 10 nM R1881. Luciferase activity was measured, normalized to protein, and presented as RLU. (F) The efficiency of MED19 knockdown was monitored at the mRNA level. Each assay was performed in triplicate, with error bars representing the standard deviation. The experiment was repeated twice with similar results.