ERBB2 and breast cancer: Among various types of breast cancer, the one with overexpression of anti-human epidermal growth factor receptor 2 (HER2) which is in nearly 30% of breast cancer located in either primary tumors or metastatic sites [3] has gained increasing attention in the last decade since its level is strongly correlated with breast cancer pathology including tumorigenesis, oncogenic transformation, metastasis, and poor prognosis [4–7].