Gene expression profiling studies have substantiated that breast cancer can be divided into distinct disorders; and four main molecular subtypes have been identified: basal-like, Human Epidermal Growth Factor Receptor 2 (HER2)-enriched, luminal A and luminal B. Several different classifiers for molecular classification of clinical breast cancer specimens into these subtypes have been developed [5-7]. Here, ERBB2 is linked to breast carcinoma.