Epidermal growth factor receptors(EGFR), p185 (neu oncogene originally identified in cell lines derived from rat neuroectodermal tumors. neu is related to but distinct from the c-erbB gene, which encodes the epidermal growth factor (EGF) receptor. It encodes a protein, designated p185, that is serologically related to the EGF receptors), ErbB3 (receptor tyrosine-protein kinase, is a membrane bound protein that in humans is encoded by the ERBB3), ErbB4 (receptor tyrosine-protein kinase, is an enzyme that in humans is encoded by the ERBB4 gene). EGFR specific ligands: transforming growth factor alfa (TGF-α), androgen receptor (AR), Neuregulin 1 (NRG1, NRG1-4), heparin-binding EGF-like growth factor (HB-EGF).