 The interaction between Ras and neurofibromin causes GAP-stimulated hydrolysis of GTP to GDP.This process depends on the stabilization of residues in the Ras switch I and switch II regions, which drives Ras into the confirmation required for enzymatic function.This interaction between Ras and neurofibromin also requires the transition state of GDP hydrolysis to be stabilized, which is performed through the insertion of the positively charged arginine finger into the Ras active site.