The finding that occurrence and development of a wide range of human cancers, including BC, positively correlate with DNMT expression [93,94,95,96], and that expression is significantly upregulated in tamoxifen-resistant BC tissues compared to sensitive ones [97], suggests these enzymes as promising therapeutic targets for treating cancer, as well as for radio- and chemo-sensitization. The gene discussed is DNMT1; the disease is cancer.