DNMT1 and cancer: DNA methylation, as a major epigenetic modification mechanism, regulates gene transcription involved in various physiological and pathophysiological processes.[28] It was mainly catalyzed by three DNA methyltransferases (DNMT), DNMT1, DNMT3A, and DNMT3B.[29] Among those DNMTs, DNMT3B is of interest because of its close links to cancer.[30] It is reported that DNMT3B is aberrantly upregulated in several cancers and contributes to many aspects of tumor progression.