Grb2 stabilizes the Shc/SHIP complex (Harmer & DeFranco 1999), presumably by simultaneously binding via its SH3 domains to SHIP and via its SH2 domain to phosphotyrosines on Shc. This forms a ternary complex of SHC1:GRB2:SHIP described as an outcome of IL-3, IL-5 or GM-CSF stimulation (Lafrancone et al. 1995, Odai et al. 1997). SHIP2 also associates with SHC1 but does not appear to require Grb2 for stability (Wisniewskiet al. 1999).