TMPRSS2 and cancer: To determine the biological activity of type 3a and type 3b AR variants, co-transfection experiments were performed with luciferase reporters carrying known AR-responsive enhancers (pGL3/PSA enhancer or pGL3/TMPRSS2 enhancer) in prostate (LNCaP, VCaP) and breast (MDA-MB-231) cancer cell lines.