Epidermal Growth Factor Receptor (EGFR) is a transmembrane glycoprotein that constitutes one of the four members of ErbB family of tyrosine kinase receptors. The epidermal growth factor receptor (EGFR) is a growth factor receptor that induces cell differentiation and proliferation upon activation through the binding of one of its ligands. The receptor is located at the cell surface, where the binding of a ligand activates a tyrosine kinase in the intracellular region of the receptor. This tyrosine kinase phosphorylates a number of intracellular substrates that activates pathways leading to cell growth, DNA synthesis and the expression of oncogenes such as fos and jun. EGFR is abnormally activated by various mechanisms like receptor overexpression, mutation, ligand-dependent receptor dimerization, ligand-independent activation and is associated with the development of variety of human cancers. EGFR inhibition is one of the key targets for cancer chemotherapy.