HMGB1 and rheumatoid arthritis: As shown in Fig. 4 G and H, stimulation of RA SFs with HMGB1 (10–500 ng/ml) for 48 hr significantly increased the productions of IL-6 and MCP-1 (by 100 ng/ml HMGB1: IL-6 to 12.00±1.76 pg/ml, P<0.05 and MCP-1 to 28.03±3.52 pg/ml, P<0.05) in culture medium, and these increases were significantly suppressed by cilostazol pretreatment (10 μM).