The ErbB2 (HER2) proto-oncogene encodes a transmembrane receptor-like glycoprotein of 185kD with intrinsic tyrosine kinase activity (1). ErbB2 does not have any known ligand. However, the kinase activity of ErbB2 can be activated without ligand if it is overexpressed and by heteromeric association with other members...

c-erbB-3/HER-3 is the third member of the type I family of growth factor receptors. It binds to ligands in the heregulin family. c-erbB-3 is over-expressed in a variety of tumors including breast, stomach, pancreas, and colon. Heregulin & EGF stimulate tyrosine phosphorylation of c-erbB-3 to different extents. ,...