EZH2 and breast cancer: To examine the function and regulation of pEZH2(T367) in breast tumorigenesis, we used MDA-MB-231, MDA-MB-468, and SUM159 breast cancer cell lines which exhibit p38-EZH2 binding, high endogenous levels of p-p3815, and high pEZH2(T367) (Supplementary Fig. 1G).