Breast cancer is classified into five subtypes, including the luminal A subtype, luminal B subtype, basal-like subtype, human epidermal growth factor receptor 2 (HER2, also known as ERBB2 or CD340) overexpression subtype, and normal breast-like subtype, according to research carried out in the last few decades (Perou et al., 2000; Sorlie et al., 2001; Sorlie et al., 2003). Here, ERBB2 is linked to breast cancer.