The over-expression of DNMTs (DNMT1, 3A, and 3B) has been shown in uterine cancer (Li et al., 2003), breast cancer (Girault et al., 2003), hepatocellular carcinoma (HCC) (Nagai et al., 2003), colorectal and stomach cancer (Kanai et al., 2001). Here, DNMT1 is linked to breast cancer.