We previously described the differential involvement of cartilage and synovium in the pathogenesis of either osteoarthritis or inflammatory arthritis, based on the co-localization of IL-1β, TNFα and iNOS58, suggesting NF-κB activation in either the cartilage or the synovium since the three markers are direct NF-κB targets27. The gene discussed is IL1B; the disease is osteoarthritis.