In addition to morphology, invasive breast cancers can also beclassified according to their proliferative potential (evaluated, e.g., by Ki67expression) or the presence of such biological factors as hormone receptors (estrogen[ER] and progesterone [PgR]) or HER2/neu overexpression that are currently usedin clinical practice to predict the prognosis and the response/resistance to cytotoxicand/or hormonal therapy [4–6]. Here, ERBB2 is linked to invasive breast carcinoma.