GATA3 and breast cancer: Because tumor development was not observed in Tg-EZH2WT mice12, we crossed Tg- EZH2T416D or Tg-EZH2WT mice with Tg-Neu mice, which can develop mammary tumors with luminal features (GATA3-positive, CK18-positive, and CK14-negative), to determine whether phosphorylation of EZH2 at T416 by CDK2 has a dominant role in basal-like lineage commitment in tumors.