U0126 attenuates spontaneous nociceptive responses, the elevation of p-Cdk5^S159 and Cdk5 activity in SCDH induced by formalin administration.

a. U0126 treatment significantly decreases the numbers of spontaneous flinches induced by formalin injection in the 2^nd phase (10–45 min), but not in the 1^st phase (0–10 min). Data were analyzed by two-way ANOVA with repeated measures followed by Bonferroni's multiple-comparison tests. b. U0126 mitigates formalin-induced p-Cdk5 increase in spinal cord in the Western blot analysis. c. Quantification of the Western blot shows that the increase of p-Cdk5^S159 by formalin is attenuated after U0126 treatment, **p<0.01. d. U0126 mitigates formalin-induced Cdk5 kinase activity in spinal cord detected by an in vitro phosphorylation assay. Histone H1 was used as a substrate. e. Quantification of Cdk5 activity (density of phosphorylated H1 band) in the SCDH, **p<0.01, ***p<0.001.