RAF1 phosphorylates MEK1 RAF1 phosphorylates MEK2 RAF phosphorylates MEK Active Raf-1 phosphorylates MEK-1/2 on Serine residues, converting ATP to ADP. The MEK-1/2 kinase is now active. Authored: Charalambous, M, 2005-01-07 11:17:43 Edited: Schmidt, EE, 0000-00-00 00:00:00 Reactome Database ID Release 43112407 Reactome, http://www.reactome.org ReactomeREACT_614 Reviewed: Dooms, H, 2011-03-17 Reviewed: Villarino, A, 2011-02-11 PathwayStep3854 PathwayStep3853