This gene encodes a member of the epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases. Amplification of ERBB3 and/or overexpression of its protein have been reported in numerous cancers, including prostate, bladder, non small cell lung cancer, endometrial cancer and breast tumors. Several ERBB3 inhibitors are under various clinical trials against different types of solid tumors, including non small cell lung cancer, breast cancer, ovarian cancer and gastric cancer.