Epidermal Growth Factor Receptor (EGFR) is a type of transmembrane protein located on the surface of cells that belongs to the family of Receptor Tyrosine Kinases (RTKs). The EGFR protein is activated by binding with specific extracellular ligands such as epidermal growth factor (EGF), transforming growth factor-alpha (TGF-α), and others. Once activated, EGFR initiates a complex signaling cascad..