HER2 is a proto-oncogene that encodes an 185 k Datrans membrane receptor tyrosine kinase which exhibits extensive homology to epidermal growth factor receptor (EGFR) .HER2 is also known as the neu and cerbB2 proto-oncogene.ER2 is a proto-oncogene that encodes an 185 k Datrans membrane receptor tyrosine kinase which exhibits extensive homology to epidermal growth factor receptor (EGFR) .