Figure 4

Involvement of p38 MAPK phosphorylation in TNF-α-induced MMP-9 expression. (A) Cells were pretreated with SB202190 for 1 h and then incubated with TNF-α (15 ng/ml) for 24 h. (B) Cells were pretreated with SB202190 (30 μM) for 1 h and then incubated with TNF-α (15 ng/ml) for 6 h. The isolated RNA samples were analyzed for the levels of MMP-9 mRNA by real-time PCR. Data are expressed as mean±SEM of three independent experiments. ^*P < 0.05; ^#P < 0.01, as compare to the cells treated with TNF-α alone. (C) Cells were pretreated with or without SB202190 (30 μM) for 1 h and then stimulated with TNF-α for the indicated time intervals. Phosphorylation of p38 MAPK was determined by Western blot using an anti-phospho-p38 MAPK antibody. (D) Cells were transfected with p38 siRNA for 24 h and then incubated with TNF-α (15 ng/ml) for 24 h. (A,D) MMP-9 expression was determined as described in Figure 1. The cell lysates were determined by Western blot using an anti-p38 MAPK or anti-GAPDH antibody.