DNMT1 and Familial prostate cancer: Subsequent studies with various Dnmt1 hypomorphic mice collectively demonstrated that genomic DNA hypomethylation has dual roles in tumorigenesis, strongly suppressing intestinal adenomas15,18, squamous tongue, and esophagus carcinogenesis58, and overall tumorigenesis in prostate cancer14, but promoting T-cell lymphoma11, intestinal microadenoma15, and early stages of prostate cancer and liver cancer14,15.