DNA methylation is established by two methyltransferases, DNMT3A and DNMT3B, and maintained by another DNA methyltransferase DNMT1 in a complex with UHRF1.[35] As shown in Figure S4B–D, Supporting Information, the expression of DNMT1, UHRF1, and DNMT3A is inversely associated with the expression of NNMT in cancer cell lines as well as in multiple types of tumors, such as glioblastoma multiforme (GBM), rectum adenocarcinoma (READ), breast cancer (BRCA), and lung squamous cell carcinomas (LUSC) as analyzed. Here, DNMT1 is linked to breast cancer.