sequence of Grb2 GRB2_HUMAN ABUNDANT SRC HOMOLOGY ASH ASH PROTEIN Adapter protein GRB2 GRB2 Growth factor receptor-bound protein 2 IMR:0002060 NCKAP2 Protein Ash SH2/SH3 adapter GRB2 UniProt:P62993 growth factor receptor-bound protein 2 molecule_role