In breast cancer research, for MDA-MB-231 and MCF-7 cell lines, after EGCG treatment, the transcriptional levels of DNA methyltransferases (DNMT1, DNMT3a, DNMT3b) were significantly downregulated, and the degree of DNA methylation in the promoter region of the tumor suppressor gene SCUBE2 decreased simultaneously. Here, DNMT1 is linked to breast cancer.