EGFR (Epidermal growth factor receptor, ErbB-1) is a receptor tyrosine kinase (RTK) that is one of four members of the EGFR/ErbB family of receptor tyrosine kinases. EGFR plays a key role in the regulation of essential normal cellular processes and in the pathophysiology of hyperproliferative diseases such as cancer. Activation of the EGFR signaling pathway has been linked with increased cell proliferation, angiogenesis, metastasis and decreased apoptosis.The GRB2 adaptor protein binds activated EGFR at phospho-Tyr1068. A pair of phosphorylated EGFR residues (Tyr1148 and Tyr1173) provide a docking site for the Shc scaffold protein, with both sites involved in MAP kinase signaling activation.