Figure 1

Effect of protein kinase inhibitors and LY83583 on endothelin-1 (ET-1)-induced MMP-13 and MMP-1 production by human osteoarthritis chondrocytes. Confluent monolayer chondrocytes were preincubated 30 min at 37°C with SB 202190 (1 μM), PD98059 (10 μM), Wortmannin (100 nM), KT5720 (4 μM) or LY83583 (2 μM) for 30 min at 37°C, and were then challenged with ET-1 for 24 hours. MMP-13 and MMP-1 proteins were measured in the culture media using specific ELISA assays. P values indicate significant differences comparing experimental conditions with ET-1 treatment alone (*) and versus the control cultures (^#). Values are expressed as the mean ± standard error of the mean of five independent experiments performed in duplicate. Significant differences: ^#, * P < 0.05; ^##, ** P < 0.01; ^###, *** P < 0.005.