Given the direct regulation of GATA3 by BRCA1 shown above, and EMT-suppressive function of ectopic GATA3 in cell lines 26-28, we hypothesized that depletion of Gata3 in mice resulted in poorly differentiated mammary tumors with the induction of EMT which phenocopied Brca1-deficient tumors. Here, BRCA1 is linked to breast cancer.