Epidermal growth factor receptor (EGFR) belongs to a family of cell surface receptors called receptor tyrosine kinases (RTKs), and is also the most studied member of this family. It is made up of an ectodomain (ECD), which contains four subdomains called DI-DIV, a transmembrane region, and a cytoplasmic tyrosine kinase domain (TKD). Binding of the ligand induces conformational changes in the ECD, which leads to the dimerization of EGFR. This results in the activation of the TKD, and the subsequent signal transduction. This receptor has a molecular weight of ～178kDa.
EGF exerts its actions by binding to the EGF receptor (EGFR), a 170 kDa glycoprotein having EGF-activated protein tyrosine kinase activity. Even in the absence of EGF-like ligands, EGFR can participate in cellular responses elicited by several other stimuli. High levels of EGFR are expressed in approximately one third of human epithelial tumors, and in the cancers of the bladder, breast or lung that have poor clinical prognosis, hence the interest in targeting EGFR.
