PRTN3 and rheumatoid arthritis: To understand the mechanism of the clinical observation that the matrix proteinase-3 concentration of patients with rheumatoid arthritis treated successfully with methotrexate does not usually normalize, we investigated the effects of A2A AdoR activation and inhibition on tumor necrosis factor-alpha (TNFα)-induced MMP-3 release by MH7A human rheumatoid synovial cells.