G9a (EHMT2) is an euchromatic histone-lysine methyltransferase that in specific situations physically interacts with DNA methyltransferase 1 (DNMT1) and the adaptor molecule, ubiquitin-like with PHD and RING finger domains 1 (UHRF1), contributing to DNA methylation, epigenetic tumor-suppressor gene silencing, and cancer cell proliferation [21–23]. This evidence concerns the gene DNMT1 and cancer.