ERBB2 and breast cancer: Breast cancer is currently divided into five subtypes by coding sequence microarray technology (Prat et al., 2015; Cejalvo et al., 2018): (1) Luminal-A type; (2) Luminal-B type; (3) human epidermal growth factor receptor 2 (HER2) overexpression type; (4) base-like type; (5) normal type.