Remember cell signaling pathways and kinase cascades? Epidermal growth factor receptor (EGFR) is a member of the ErbB family of ligand-activated tyrosine kinase receptors. These play roles in the proliferation of various cells, such as fibroblasts as well as oncogenesis. Once EGFR binds to its ligand, EGF, this causes the receptor to dimerize and undergo autophosphorylation on multiple tyrosine residues. Then, the protein Shc binds and is quickly phosphorylated by EGFR on its tyrosine residue. P