DNMT1 and breast carcinoma: Interestingly, the synergistic inhibitory effects of hypermethylated E2F1 motif, histone modification H3K9ac and transcription factor E2F1 were primarily observed in cells originating from BRCA1-mutated breast cancer, but transformed cell lines (293 T) and non-mutated breast cancer were insensitive to the loss of H3K9ac and E2F1 enrichment around the E2F1 motif in the core promoter of DNMT1.