Therefore, we chose eight different BC cell lines, representing the three main subfamilies: Luminal A/B (MCF-7, T47D and ZR-75-1), TNBC (HS-578-T, MDA-MB-231, Cal-51 and BT20) and HER2+ (SKBR3) and analysed protein expression levels of the most common pro-and anti-apoptotic proteins. This evidence concerns the gene ERBB2 and breast cancer.