Fig. 2.

Inhibition of JNK MAPK by SP600125 inhibits PGN-induced iNOS expression and NO production. Mouse peritoneal macrophages were cultured with or without various concentrations of SP600125 (10, 30, or 50 μM) for 30 min, washed, and then treated with PGN (10 μg/ml) for 30 min, 6 h, or 18 h. (A) After 30 min, the phosphorylation of c-Jun was determined by immunoblotting in cell lysates with an antibody against phospho c-Jun or c-Jun. (B) After 18 h, NO production in culture supernatants of mouse peritoneal macrophages was evaluated by using the Griess reagent assay. Each bar represents the standard error of three independent experiments. *, P < 0.05 compared to PGN. (C) After 6 h, RNA was isolated and checked for iNOS transcripts by real-time RT-PCR. Each bar represents the fold expression relative to untreated macrophages. The data represent the means ± the SD of three independent experiments. #, P < 0.01 compared to control macrophages. (D) After 18 h, macrophages were lysed, and lysates were immunoblotted with a polyclonal anti-iNOS antibody. The same blot was reprobed with anti-actin antibody to demonstrate equal protein loading.