ERBB2 and breast cancer: Further low-molecular-mass drug molecules targeted on critical cancer targets include the epidermal growth factor receptor (EGFR) kinase inhibitors gefitinib and erlotinib for non-small-cell lung cancer (NSCLC) patients, and the vascular epidermal growth factor receptor (VEGFR) kinase inhibitor sorafenib for the treatment of renal cancer, along with the EGFR/ERBB2 inhibitor lapatinib for ERBB2-positive breast cancer [56].