However, germline or mammary epithelium-specific deletion of Gata3 [17, 18, 30, 31] in mice results in early lethality or growth defects and targeted deletion of GATA3 in tumor cells leads to apoptosis [28], making it difficult to determine the mechanism of loss-of-function of Gata3 in activation of EMT in mammary tumor initiation and progression. Here, GATA3 is linked to breast cancer.