Figure 1.

Effects of rolipram, IBMX and 8-Br-cAMP on MKP-1 expression and p38 MAPK phosphorylation in activated J774 macrophages. (A) J774 cells were stimulated with LPS (10 ng·mL⁻¹) in the presence or absence of rolipram (2 μM), IBMX (100 μM) or 8-Br-cAMP (100 μM) for 1 h. MKP-1 mRNA was detected by quantitative RT-PCR, and MKP-1 mRNA expression levels were normalized against GAPDH mRNA levels. The results are expressed as mean ± SEM, number of repeats = 6. J774 cells were stimulated with LPS (10 ng·mL⁻¹) in the presence or absence of rolipram (2 μM) or BIRB 796 (100 nM) and (B) MKP-1 protein (at 1 h), (C) phosphorylated p38 MAPK (at 30 min) and (D) phosphorylated MK2 (at 30 min) were detected by Western blot. The chemiluminescent signal was quantified and the amounts of MKP-1 and phosphorylated p38 MAPK or MK2 were normalized against actin and total p38 MAPK or MK2 respectively. Phosphorylated p38 MAPK and MK2 levels are expressed in arbitrary units, LPS-simulated cells were set as 100%, and the other values were related to that value. The results are expressed as mean ± SEM; number of repeats = 4 for MKP-1 and MK2 and number of repeats = 6 for p38 MAPK. One-way anova with Bonferroni's post-test was performed and statistical significance is indicated as **P < 0.01 and ***P < 0.001.