Our finding that suggests Brca1 protects the Gata3 promoter from methylation is, at least, one of the important mechanisms by which BRCA1 regulates GATA3 transcription, though it remains to be investigated that whether BRCA1 directly transactivates GATA3 and how BRCA1 interacts with DNA methyltransferases (DNMTs) and EZH2 to control transcription of GATA3. Our findings also suggest that DNMT inhibitors can be used to induce GATA3 and its mediated differentiation for treatment of BRCA1-deficient breast cancers. This evidence concerns the gene DNMT1 and breast cancer.