p21 RAS:GTP p21 RAS:GDP NCAM1:pFAK:Grb2:Sos-mediated nucleotide exchange of Ras Authored: Garapati, P V, 2009-02-24 10:31:15 Edited: Garapati, P V, 2009-02-24 10:58:20 Pubmed12639709 Pubmed8493579 Reactome Database ID Release 43392054 Reactome, http://www.reactome.org ReactomeREACT_18366 Reviewed: Maness, PF, Walmod, PS, 2009--0-5- The guanine nucleotide exchange factor SOS interacts with GRB2 bound to phosphorylated FAK bound to NCAM. Upon formation of this complex, SOS activates Ras by promoting GDP release and GTP binding.