PTGS2 and rheumatoid arthritis: Further experiments demonstrated that inhibition of the COX enzyme prevented the production and release of PGE-2 in rheumatoid synovial fibroblasts [28], and the PGE-2 processing enzymes were identified by RT-PCR or Western blot as COX-1, COX-2, and PGES-1 within the synovium of RA [23, 25, 28, 29] and of OA patients [12, 30, 31].