In breast cancer, the subtype determined by immunohistochemistry of estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor type 2 (HER2) is one of the prognostic factors as well as a factor in the clinical stage, histological grade, and the marker Ki-67 [10–12]. The gene discussed is ERBB2; the disease is breast carcinoma.