Vav3 enhances AR3 (AR-V7) transcriptional activity. AR-negative human prostate cancer cell line PC3 was transfected with reporter plasmid ARE-Luc and Vav3 [or equivalent amounts of the corresponding empty vector (EV) and AR or AR3 (A)] or ARv567es (B). Cells were treated with either vehicle (−) or 1 nm R1881 (+). Luciferase activity (RLU) was determined 48 h after transfection. Data represent one of four experiments performed in triplicate, plotting the mean RLU/protein ± sem. Significance was determined using a two-tailed Student's t test. *, P < 0.05. C, LNCaP cells stably expressing either GFP or Vav3 were transfected with AR3 or equal amounts of EV. Cells were grown in 2% CSS for 48 h. RNA was extracted and reverse transcribed to cDNA, and real-time PCR was done with TaqMan probes for KLK3 (PSA), FKBP5, and HPRT1 (control). Data represent four independent experiments performed in triplicate. *, P < 0.05.