This statement is supported by the observations obtained by employing either ERα antibody that specifically recognizes ERα outside of the nucleus of breast cancer cells (i.e., anti-ERα Sp-1 antibody) {[19] and present results} or an ERα mutant (i.e., H2_NES - Nessi) that is abundantly and artificially located in the cytoplasm {[21] and present results}. This evidence concerns the gene ESR1 and breast cancer.