TNF and rheumatoid arthritis: Previous studies suggest that: (1) TNF-α is expressed at high levels in the inflamed synovium, particularly at the cartilage-pannus junction of RA patients [11]–[13]; and (2) TNF-α inhibitors (eg. infliximib, adalimumab, and etanercept-a recombinant hTNF receptor (p75)-Fc fusion protein) have been used in the RA treatment in clinical practice [14], [15].