Figure 6

p38 inhibition suppresses OSM-induced IL-6 induction; p38 inhibition suppresses OSM-induced IL-6 mRNA expression. (a) RA-FLS pretreated with vehicle (DMSO-), PD98059 (ERK1/2 pathway inhibitor), SB203580 (p38 inhibitor), and SP600125 (JNK inhibitor) for two hours. Cells were then stimulated with OSM (20 ng/ml) for 24 hours, after which conditioned media were collected and IL-6 content was measured by ELISA. The data were expressed as the mean ± SD of three independent experiments. *P < 0.01 compared to OSM-treated RA-FLS. **P < 0.001 compared to OSM-treated RA-FLS. (b) RA-FLS pretreated with vehicle (DMSO-) or SB203580 (p38 inhibitor), for two hours. Cells were then stimulated with OSM (20 ng/ml) for four hours, after which IL-6 and GAPDH mRNA expression was determined by real-time PCR method. The data were expressed as the mean ± SD of two independent experiments. *P < 0.05 compared to OSM-treated RA-FLS. **P < 0.01 compared to OSM-treated RA-FLS.