Figure 4. HDM extract-induced NO production involves the TLR2- and TLR4- associated MyD88 signaling pathways and is blocked by p38MAPK and MEK-1, -2 inhibitors.

(A) Analysis of phosphorylation of IRAK-1 and MKK. Cellular extracts from HDM extract-stimulated MH-S cells (6x10⁶ cells/mL) were evaluated for p-IRAK-1 and p-MKK protein expression by western blot. (B) Cells were pre-treated with increasing doses of U0126 and SB203580, a MEK-1/2 and a p38MAP kinase inhibitor respectively, for 4 h, and then stimulated with HDM extract for 24 hours. Accumulation of NO in supernatants was evaluated with the Griss Reagent. All samples were analyzed in triplicate. Each bar represents the mean ± SEM of nitrite levels in three replicate wells.