AR and prostate cancer: Indeed, KMT5A siRNA-mediated knockdown inhibits prostate cancer cell proliferation and KMT5A has been identified as an AR-interacting protein that is required for the transcription of the AR-regulated gene, prostate specific-antigen (PSA), via the promotion of mono-methylation on histone H4 at lysine 20 (H4K20Me1) at the PSA promoter [4].