Potent and selective non-competitive inhibitor of MAP kinase kinase. Inhibits MEK-1 and MEK-2 (IC50 values of 0.07 and 0.06 μM respectively) with little or no effect on the activities of PKC, Abl, Raf, MEKK, ERK, JNK, MKK-3, MKK-4/SEK, MKK-6, Cdk2 or Cdk4. Centrally active following systemic administration in vivo. Also available as part of the MAPK Cascade Inhibitor Tocriset™ and MAPK Inhibitor Tocriset™. Negative control U0124 (Cat. No. 1868) also available.