In breast cancer samples DNMT1, DNMT3A, DNMT3B levels were increased 1.8–2.9 fold compared to normal tissue [179], tumor suppressor proteins: cyclin-dependent kinase inhibitor p16 which inhibit Cdk4 (p16INK4a) and alternate reading frame p14 protein (p14ARF) were inactivated [181], while the BRCA1 gene was epigenetically silenced and deleted [182]. This evidence concerns the gene DNMT3A and breast cancer.