ESR1 and breast carcinoma: Nuclear localization of the protein was seen in different tumors [110, 119, 120], and recruitment of ACTN4 to the pS2 promotor, an estrogen receptor (ER) target in the ER-positive breast cancer cell line MCF7, suggested that ACTN4 may play a role in E2-mediated regulation of breast cancer proliferation [121, 122].