KLF4 and Familial prostate cancer: FOXA1, an AR cofactor, can cooperate with AR to mediate gene expression in prostate cancer.24, 25, 26 To determine whether AR and FOXA1 effectively bind to the KLF4 promoter, we performed quantitative reverse-transcription PCR (qRT–PCR) analysis in LNCaP cells after a chromatin immunoprecipitation (ChIP) assay by using anti-AR and anti-FOXA1 antibodies.