ERBB2 and cancer: Human epidermal growth factor receptor 2 (HER2) is a receptor tyrosine kinase overexpressed on many cancer cells; a trimeric anti-HER2 aptamer derived from the degradation of HER2 in lysosomes had previously been discovered to kill HER2-overexpressing cells, likely by causing cross-linking, internalization, and degradation of HER2 [23].