BRCA1 and neoplasm: Taking into consideration our previous discovery that Brca1 positively regulates GATA3 expression and GATA3 functions downstream of BRCA1 suppressing luminal-to-basal and mesenchymal differentiation in mammary cells as well as tumor development and progression [31, 32], our findings demonstrate that GATA3 functions downstream of BRCA1 to promote HR-mediated DNA damage repair and to suppress aberrant differentiation in mammary and tumor development.