The relatively new and evolving molecular classification uses immunohistochemistry (IHC) to identify receptors including estrogen (ER), progesterone (PR), and human epidermal growth receptor (HER)2/neu expression which are critical for planning targeted treatment regimes.4, 5, 6, 7In 2000, Perou et al first described the “molecular portrait” of breast cancer which included luminal A, luminal B, and HER2/neu overexpression, as well as basal-like.8Eleven years later, the St. The gene discussed is ERBB2; the disease is breast cancer.