ERBB2 and breast cancer: We validated various expression levels of HER2 in four EpCAM-overexpressed breast cancer cell lines by flow cytometry (FCM) and Western blot analysis, the strongest in SK-BR-3, moderate in MDA-MB-453, low in MCF-7, and negative in MDA-MB-468 cells (Figure 1A, Supplementary Figures S2A,B).