U0126 is a selective MAP Kinase Kinase inhibitor, displaying a preference for MEK-1 (IC50 = 72 nM) and MEK-2 (IC50 58nM). It is known that U-0126 binds to MEK in a noncompetitive manner compared to ATP. Studies suggest that U-0126 antagonizes the transcription of AP-1, via the inhibition of MEK. In addition, U-0126 has been observed to inhibit promoters containing an AP-1 response element, while in contrast having no effect on promoters that lack an AP-1 response group. U-0126 is also useful in neuronal studies in mice since it displays inhibitory effects against oxidative stress. U-0126 is an activator of PGC-1, mtTFA and nuclear respiratory factor.