Loss of FOXA1 expression by targeted siRNA transfection in breast and prostate cancer cell lines results in reduction of growth suggesting an essential role in the proliferation of both cancers (Hurtado et al., 2011; Robinson et al., 2011; Zhang et al., 2011) yet the mechanistic role for FOXA1 in ER and AR biology appears to be different. This evidence concerns the gene AR and prostate carcinoma.