Dual Specificity Phosphatase 1 Regulates Human Inducible Nitric
Oxide Synthase Expression by p38 MAP Kinase
The effect of DUSP1 siRNA on DUSP1 expression and p38 MAPK phosphorylation in A549 and J774 cells. (a) A549 cells were transfected with DUSP1-specific siRNA 1 or 2 (DUSP1 siRNA 1 or 2), nontargeting control siRNA (control siRNA), or Lamin A/C-specific siRNA (Lamin A/C siRNA). (b) J774 cells were transfected with DUSP1-specific siRNA (siMKP-1) or nontargeting siRNA (siNEG). Cells were stimulated with cytokines (CM: TNF, IFNγ, and IL-1β; 10 ng/mL each) or LPS (10 ng/mL) for 1 h. DUSP1 mRNA expression was determined by quantitative real-time RT-PCR and normalized against GAPDH mRNA. DUSP1 protein expression and p38 MAPK phosphorylation were determined by Western blot. Chemiluminescent signal was quantified and DUSP1 expression was normalized against actin, and phosphorylated p38 MAPK was normalized against total p38 MAPK. Results are expressed as a percentage of CM or LPS. One-way ANOVA with Bonferroni’s posttest was performed, and statistical significance is indicated with , , and , , except for DUSP1 mRNA in J774 cells, .