TNF and osteoarthritis: We measured chondrocyte expression of key osteoarthritis-associated factors such as matrix metalloproteinase 13 (MMP-13), nitric oxide (NO), collagen II, nuclear factor kappa-light-chain-enhancer of activated B cells p65 (NF-κB p65) as well as the expression of inflammatory mediators in chondrocytes such as interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS).