Protein production of tumor necrosis factor (TNF)-α, IL-6, IL-8, and matrix metalloproteinase 9 (MMP9) by monocyte-derived macrophages from healthy controls (n = 8, open squares) and rheumatoid arthritis patients (n = 9, filled squares). Cells were stimulated with LPS for 24 hours and pretreated 1 hour beforehand with RWJ 67657 at various concentrations. Protein production was measured in supernatants by ELISA and is expressed in ng/ml (a). Inhibition was calculated against the stimulated control (b). Bars show mean and SEM. *P < 0.05; **P < 0.001, paired t-test, calculated versus the stimulated control. unst, unstimulated.