ERBB2 and breast cancer: We examined Human Epidermal Growth Factor Receptor 2 (HER2) positive breast cancers as not only is this RTK overexpressed in 25%–30% of breast cancers, but also 70% of patients develop resistance to the current frontline therapy, the HER2-targeted monoclonal antibody, trastuzumab (Moore et al., 2014, Slamon et al., 2001).