Casp8 downregulates AR transcriptional activity in a dosage-dependent manner. pGL3-4 × ARE-E4-Luc (A), pGL3-PSA(E)-E4-luc (B), or pGL3-4 × Gal4-E4-luc (C) reporter (100 ng), pcDNA-AR (30 ng) or pcDNA-Gal4-p53 (10 ng) and indicated amounts of pcDNA-Casp8 were cotransfected into PC3mm2 cells. Transfected cells were grown in the absence or presence of 10 nM R1881 for 48 h. Cells were then harvested for luciferase assay (top panel), RT–PCR (middle panel), and Western blot analysis (bottom panel). Values represent mean±s.d. (N=3).