DNMT1 and breast carcinoma: Additionally, genome-scale methylation studies identified that the gene of insulin gene enhancer protein, ISL1, was hypermethylated and downregulated by DNMT1 in breast cancer and BCSCs, and inhibition of DNMT1 or ISL1 overexpression in triple-negative breast cancer (TNBC) cells (CAL51) suppressed CSC populations [78].