IL-1β induced gene expression in synovial fibroblasts (SFB). SFB (six different preparations from six different donors) were cultured with DMEM containing recombinant human IL-1β (1 ng/ml) for 24 h. The SFB were washed three times with DMEM, and the medium was switched to fresh DMEM containing 10% FBS. After incubation for 24 h, gene expression was analyzed by real-time PCR. Data are the means ± standard error of the mean. Comparison of mean values was performed by Mann-Whitney U-test; *P <0.05 versus non-stimulated SFB. NS, no significant change; MMP, matrix metalloproteinase; VEGF, vascular endothelial growth factor.