ERBB2 and cancer: Although most clinical focus has been on EGFR and ERBB2 due to their aberrant activation in many human malignancies [7], overexpression of ERBB3 often co-occurs with EGFR or ERBB2 in many types of cancers such as breast [8,9], colorectal (CRC) [2,10], gastric [11,12], ovarian [13], and pancreatic [14].