ERBB2 and breast neoplasm: Breast tumors can be divided into different molecular subtypes: i) the Luminal A and B subtypes, expressing high levels of estrogen and/or progesterone receptors, ii) the HER2+ subtype, overexpressing the human epidermal growth factor receptor 2 (HER2) protein and iii) the triple-negative breast cancers (TNBC), expressing none of the hormone receptors and showing no HER2 amplification and/or overexpression [2, 3].