ESRP1 and breast cancer: In addition, breast cancer cells treated with 5-aza-2′-deoxycytidine (5-Aza-dc), an established DNA methylation inhibitor [31], reduced the methylation level of the E2F1 binding site (Fig. 3G), which, in turn, restored the E2F1 binding on the ESRP1 promoter (Fig. 3H).