ESR1 and breast cancer: For confirmation, we tested expression of both PKCζ and phospho-PKCζ in a cohort of human breast cancer samples consisting of normal breasts, ductal carcinoma in situ (DCIS), invasive ductal carcinomas (IDCs) of ER-positive, HER2-positive, and TNBC subtypes, and metastatic breast cancers (Fig. 6a,b).