Effects of mitogen-activated protein kinase (MAPK) inhibitors on S100A8/A9-mediated cytokine production. Monocytes from healthy individuals (1 × 106 cells per ml in culture medium with 10% fetal calf serum) were preincubated for 2 hours in the presence of the MAPK inhibitors PD98059, SB202190, and SB203580 and the negative control SB202474 (1 μM) and were then stimulated for 24 hours with or without S100A8/A9 (0.1–10 μM) in the presence of polymyxin B (100 μg/ml). Culture supernatants were measured for cytokines by cytometric beads array. Values are the mean ± standard error of the mean. IL, interleukin; n, number of samples tested; TNF-α, tumor necrosis factor alpha.