Effect of adiponectin on the expression of vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-1, and MMP-13 in rheumatoid arthritis fibroblast-like synoviocytes. Adiponectin stimulates the expression of (a) VEGF and (b) MMP-1 and MMP-13 at a level comparable to 1 ng/mL interleukin-1-beta (IL-1β). The data shown are representative of three independent experiments, and similar results were obtained from all three. Values are expressed as mean ± standard error of the mean. * P < 0.05, ** P < 0.01 versus nontreated group.