PI3K catalytic subunit binds to GRB2:GAB1:PI3Kreg (indirect) Authored: Rothfels, K, 2011-08-15 Pubmed11353842 Pubmed15863030 Reactome Database ID Release 431268265 Reactome, http://www.reactome.org ReactomeREACT_111233 Reviewed: Gotoh, N, 2011-08-26 The 110 kDa catalytic subunit (PIK3CA) binds to the 85 kDa regulatory subunit (PIK3R1) to create the active PIK3. Activated FGFR:p-FRS2alpha:p-SHP2:GRB2:GAB1:PI3KR1 Activated FGFR:p-FRS2alpha:p-SHP2:GRB2:GAB1:PI3K