ERBB2 and neoplasm: To ameliorate their characterization, we have conducted a comparative metabolomic study on a panel of cell lines representative of the most frequent tumor subtypes, identified based on the current histopathological and molecular classifications: namely, the SK-Br-3 cell line, showing HER2-enriched phenotype (15–20% of tumors), and the T-47D and MCF-7 cell lines, belonging to the luminal A phenotype (which account for 50–60% of breast tumors) [1].