Adhesion of monocytes to collagen stimulates a p38-dependent increase in IL-1β production. THP-1 cells were either untreated or treated for 30 min with SB202190 (100 nM), PP2 (5 μM), γ-secretase inhibitor (10 μM), β-secretase inhibitor (5 μM) or DMSO vehicle. Cells were then plated on tissue culture plastic or collagen for 24 hours. Media were collected and analyzed by human interleukin-1β ELISA. Data were analyzed by unpaired ANOVA with Tukey's post-test comparison and are expressed as mean +/- SD (* = p < 0.001 from control, ** = p < 0.01 from collagen, *** = p < 0.001 from collagen). Values are representative of three independent experiments.