Epidermal Growth Factor Receptor antibody (EGFR) is a transmembrane glycoprotein receptor tyrosine kinase and is activated by EGF. The carboxy terminal tyrosine residues on EGFR, Tyr1068, Tyr1148 and Tyr1173 are major sites of autophosphorylation, which occurs as the result of EGF binding. Once activated, phosphotyrosines mediate the binding of growth factor receptor-binding protein-2 (Grb2) to the EGFR. This antibody only detects EGFR phosphorylated on Tyrosine 1068 of the mature human isoform. Over-expression of EGFR has been reported in tumors of breast, lung, colon, cervix, ovary, esophagus and endometrium.