DNMT1 and breast cancer: The altered expression of DNMTs, encoding DNMTs (DNMT1, DNMT3a, and DNMT3B) could result in global changes of methylation in leukemia cells and breast cancer stem-like cells [36, 37], while DNMT1, DNMT3A, and DNMT3B are all upregulated in most cancer types (8, 6, and 9, respectively) in this study.