Next, we evaluated the expression of ERBB2 and the effects of T-DM1 across 6 HER2+ (HCC1954, ZR-75-30, BT-474, SK-BR3, HCC1569 and MDA-MB-453) and 3 HER2-negative BC cell lines (MCF7, T-47D and MDA-MB-468) (Figure 3a,b). The gene discussed is ERBB2; the disease is breast cancer.