p21 RAS:GTP p21 RAS:GDP Ras nucleotide exchange mediated by GRB2-SOS1 bound to FGFR mutants Activation of Erk1/2 downstream of FGFR mutants suggests that, as is the case for WT FGFR, FGFR mutant-associated SOS1 activates RAS nucleotide exchange from the inactive GDP-bound to the active GTP-bound state (see for instance, Weiss, 2010; Dutt, 2011; Raffioni, 1998; Cha, 2009; Hart, 2000; Turner, 2010; Kunii, 2008; Byron, 2008; Roidl, 2010; Chesi, 2001; Ronchetti, 2001; reviewed in Wesche, 2011). Authored: Rothfels, K, 2012-02-09 Edited: Rothfels, K, 2012-05-16 Pubmed11157491 Pubmed11429702 Pubmed18381441 Pubmed18757403 Pubmed19103595 Pubmed19946327 Pubmed20179196 Pubmed21160078 Pubmed21666749 Pubmed21711248 Pubmed9857065 Reactome Database ID Release 431982085 Reactome, http://www.reactome.org ReactomeREACT_120761 Reviewed: Ezzat, S, 2012-05-15