Effect of MAPK inhibitors on TLR3- and TLR9-mediated proinflammatory cytokine secretion. Peritoneal macrophages were pretreated with the indicated concentrations of MAPK inhibitors SP 600125 (SP), PD 98059 (PD), and SB 203580 (SB) for 1 hour followed by stimulation with (A) Poly (I:C) or (B) CpG for 24 hours. The effect of MAPK inhibitors was compared with inhibitory effect of Dex on cytokine secretion. Macrophages pretreatment with Dex for 3 hours was followed by Poly (I:C) or CpG treatment for 24 hours. Concentrations of IL-6, TNF-α, and IL-12 in the culture media were measured. Data are shown as mean ± SEM; n = 4; *P < .001; **P < .01; and ***P < .05 for Dex or MAPK inhibitor(s)–treated macrophages compared with treatment group treated with Poly (I:C) or CpG only.