Dual Specificity Phosphatase 1 Regulates Human Inducible Nitric
Oxide Synthase Expression by p38 MAP Kinase
The effect of p38 MAPK inhibitors BIRB 796 and SB202190 on iNOS expression and NO production in response to cytokine mixture in A549 cells. A549 cells were preincubated with increasing concentrations of (a) BIRB 796 or (b) SB202190 for 30 min and stimulated with a cytokine mixture (CM: TNF, IFNγ, and IL-1β; 10 ng/mL each) for 24 h. iNOS expression was detected by Western blot. The gels are representatives of six separate experiments with similar results. Chemiluminescent signal was quantified, and iNOS (iNOS) expression was normalized to actin. NO production was measured as nitrite accumulated in the culture medium by Griess reaction. The results are expressed as mean ± S.E.M., . One-way ANOVA with Dunnett’s posttest was performed, and statistical significance is indicated with and compared to cells treated with CM.