... AllERBB proteins have four functional domains: an extracellular ligand-binding domain; a transmembranedomain; an intracellular tyrosine kinase domain; and aC-terminal regulatory domain [2]. The ... and ERBB4 (including betacellulin, heparin-binding EGF and epiregulin); and (c) neuregulin (NRG) (also knownas heregulin) that binds to ERBB3 and ERBB4.NRG1 and NRG2 bind to both ERBB3 and ERBB4,whereas ... overexpression and cancerEGFR is expressed in a variety of human tumors,including those in the lung, head and neck, colon,pancreas, breast, ovary, bladder and kidney, and in gliomas. EGFR expression and...