ERBB2 and breast carcinoma: The four breast cancer molecular subtypes, Luminal A, Luminal B, HER2+ and Basal-like, are classified according to their gene expression profiles and they represent different cancer manifestations, with distinct molecular traits, genomic alterations, and prognosis (Perou et al., 2000; Prat and Perou, 2011; Berger et al., 2018).