IL-1Rrp2 expression by hSFs and hACs. The left panels show a RT-PCR analyses of IL-1Rrp2 expression by (a) hSFs and (b) hACs treated or not treated for 8 hours by IL-1β (1 ng/ml) and/or TNF-α (10 ng/ml), as detailed under Materials and method and in Table 1. The images show representative agarose gel electrophoresis of PCR products. The right panels show real-time PCR analysis of IL-1Rrp2 mRNA levels in hSFs and hACs stimulated (black columns) or not stimulated (white columns) for 8 hours with IL-1β (1 ng/ml) and TNF-α (10 ng/ml). The amount of 28S rRNA was monitored as an internal control. The expression of IL-1Rrp2 mRNA was corrected for 28S rRNA levels and the IL-1Rrp2/28S ratios were normalized to the maximal value observed in each experiment, which was set to 100%. The results shown represent the mean ± standard error of data obtained with samples from three (hSFs) or four (hACs) independent cultures. IL, interleukin; IL-1Rrp2, IL-1 receptor related protein 2; hAC, human articular chondrocyte; hSF, human synovial fibroblast; RT-PCR, reverse transcriptase polymerase chain reaction; TNF, tumour necrosis factor.