Breast cancer can be divided into 4 molecular subtypes, including luminal-A, luminal-B, human epidermal growth factor-2 overexpressed (HER2-OE), and basal-like (Triple-negative breast cancer; TNBC) based on the expression of the Kiel-67 (Ki-67) protein, and the estrogen (ER), progesterone (PR), and HER-2 receptors (24). The gene discussed is ERBB2; the disease is breast cancer.