Selective inhibitor of the mitogen-activated protein kinase kinases, MEK-1 and MEK-2, with 100-fold higher potency than PD 98059, but is, at most, a weak inhibitor of PKC, Raf, ERK, JNK, MEKK, MKK-3, MKK-4/SEK, MKK-6, Abl, Cdk2 and Cdk4. U0126 is an inhibitor of AP-1 transactivation in cell-based reporter assays. J. Biol. Chem. 273: 18623-18632 (1998).
