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. Phosphorylation of residue Thr654 (removal of the signal peptide) during PKC activation prevents binding of calmodulin.