EGFR and colorectal cancer: EGFR is the first receptor target against which monoclonal antibodies (mAbs), including cetuximab (a mouse-human chimeric mAb; IgG1) against colorectal cancers and head and neck cancers, panitumumab (a fully human mAb; IgG2) against colorectal cancers, and necitumumab (a fully human mAb; IgG1) against nonsmall cell lung cancers, have been developed for cancer treatment.(5–7) Anti-EGFR mAbs possess several functional mechanisms, including antibody-dependent cellular cytotoxicity (ADCC), complement-dependent cytotoxicity (CDC), blocking dimerization or ligand binding, and EGFR endocytosis.