Conversely, specific inhibition of DNMT1 induces re‐expression of ERα in ERα‐negative human breast cancer cells.47 Both the DNMT1 inhibitors 5‐aza‐dC and zebularine reactivate functional ERα expression in MDA‐MB‐231 cells.29, 48 Furthermore, ERα can specifically interact with ISL1 in the female rat hypothalamus.49 However, the relationship between ERα and ISL1 requires further investigation. This evidence concerns the gene ISL1 and breast cancer.