TNF and rheumatoid arthritis: In the meantime, there are some studies available of differential gene expression between RA and osteoarthritis (OA) synovial membranes (SMs) [4-6], RA and OA SFBs [7] or about the effects of mediators with a central role in RA, for example, tumor necrosis factor-α and IL-1β, on SFBs [8-10].