Berotti et al. found that amplification of the Erb-B2 receptor tyrosine kinase 2 (ERBB2) gene is a determinant of the driver of cetuximab resistance and predicts the response to epidermal growth factor receptor (EGFR) and HER-2-targeted therapies in a colon cancer PDX model [62]. The gene discussed is EGFR; the disease is malignant colon neoplasm.