The epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2), pioneer members of the receptor tyrosine kinase subfamily, are frequently mutated and/or overexpressed in several types of human cancers, including nonsmall cell lung cancer (NSCLC) and breast cancer, which are leading causes of cancer-related deaths worldwide. Here, ERBB2 is linked to cancer.