The PAM50 classification scheme by Parker et al.7 builds upon the seminal work by Perou et al.8 and defines five molecular subtypes in breast cancer: (1) basal-like (Basal), (2) HER2-enriched (HER2E), (3) luminal A (LumA), (4) luminal B (LumB), and (5) normal-like (Normal). The gene discussed is ERBB2; the disease is breast cancer.