PTGES and rheumatoid arthritis: Similarly, adiponectin is able to stimulate the production of PGE2, IL-6, IL-8, vascular endothelial growth factor (VEGF), MMP-1 and MMP-13, cyclooxygenase 2 (COX-2), and microsomal prostaglandin E synthase 1 (mPGES-1) [24, 25] in RA synovial fibroblasts (Figure 1).