ERBB2 and breast neoplasm: Breast tumors can be classified in clinical practice as hormone receptor and/or HER2 positive (HR+ and/or HER2+) vs negative (HR- and/or HER2-) by immunohistochemical detection or as luminal A, luminal B, HER2-enriched and basal-like according to transcriptome profiling using gene signatures such as PAM50 [2].