Cytoplasmic target proteins containing the SH2 domain can bind to activated EGFR. One such protein, growth factor receptor-bound protein 2 (GRB2), can bind activated EGFR with its SH2 domain whilst in complex with SOS through its SH3 domain. GRB2 can bind at either Y1068 and/or Y1086 autophosphorylation sites on the receptor (Batzer et al. 1994, Okutani et al. 1994).