ESR1 and breast neoplasm: The ER-estrogen-FOXA1-GATA-3 axis has a determining function in the beginning and/or progression of luminal-type tumors, and this has recently been proposed by the attestation of FOXA1 as a pioneer factor, essential for the expression of the bulk of estrogen-inducible genes, like a breast tumor (Figure 1) [22,23].