The protein encoded by the EGFR gene is a transmembrane glycoprotein that is a member of the protein kinase superfamily. This protein is a receptor for members of the epidermal growth factor family. EGFR is a cell surface protein that binds to epidermal growth factor. Binding of the protein to a ligand induces receptor dimerization and tyrosine autophosphorylation and leads to cell proliferation. Mutations in this gene are associated with lung cancer. Overexpression of the EGFR protein occurs across a wide range of different cancers. This upregulation appears to be frequently associated with adverse prognosis. Mutations of the EGFR gene occur in a range of cancers, and these often cause the overexpression of the EGFR protein.

The epidermal growth factor receptor (EGFR) is one of the major oncogenes identified in a variety of human malignancies including breast cancer (BC). EGFR-mutations have been studied in lung cancer for some years and are established as important markers in guiding therapy with tyrosine kinase inhibitors (TKIs).