ESR1 and breast cancer: ER-α, but not ER-β knockdown significantly decreased miR-196a expression only in MCF7 cells with or without E2 treatment, indicating that ER-α, but not ER-β, is necessary for E2-induced miR-196a expression in ER+ BC cells (Fig. 3c and d; Additional file 4: Figure S4 A and B).