Some of these tumor suppressor genes inactivated by cytosine methylation on their promoters are p14ARF, APC, MLH1, and MGMT in colon cancer [1], DAPK in bladder superficial carcinoma [2], CDKN2B in leukemia and lymphoma [1], GSTP1 in prostate cancer and hepatocarcinoma [3], Caspase-8 in neuroblastoma [4], and RASSF1A in medulloblastoma, Wilms' tumor, and neuroblastoma [5]. The gene discussed is RASSF1; the disease is prostate cancer.