Figure 4. C5a regulates TLR4-induced IL-6 and IL-8 expressions through the activation of ERK1/2. ARPE-19 cells were stimulated with LPS (100 ng/ml) in the absence or presence of C5a (50 ng/ml) for 30 min. A: Representative histograms for the phosphorylation of MAPK are shown at 30 min. B: The MFI of phosphor-ERK1/2, JNK, and P38. C5a was added to the culture 10 min before LPS challenge. Inhibitors of JNK (SP = SP600125, 10 uM), ERK1/2 (PD = PD98059, 20 uM), and P38 (SB = SB239063, 20 uM) were added 1 h before LPS stimulation. C and D: Contribution of ERK1/2, JNK, and P38 to the effect of C5a on TLR4-induced IL-6 (C) and IL-8 (D) expressions. The data are expressed as the mean±SD of three independent experiments. Statistical analysis was performed using a one-way ANOVA (* indicates p<0.05 and ** indicates p<0.01).