Similarly, to clarify whether promoter methylation would also contribute to the HNF4α silencing, we treated prostate cancer cells (PC-3, LNCaP, and ARCaPM) with a DNA methyltransferase inhibitor 5-aza-2′-deoxycytidine (5-aza-dC), followed by quantitative methylation-specific PCR (qMSP) analysis. The gene discussed is HNF4A; the disease is prostate cancer.