Figure 2. Effects of IL-1β, TNF-α, and TBHP on mouse chondrocytes. (A) The cytotoxic effect of IL-1β (1 and 5 ng/ml), TNF-α (1 and 5 ng/ml), and TBHP (50 and 100 μM) treatment on chondrocytes for 24 h was determined using a CCK8 assay. (B, C) After the indicated treatment for 24 h, the effects of IL-1β (5 ng/ml), TNF-α (5 ng/ml), and TBHP (100 μM) on the expression of MMP13, Collagen II, iNOS, and cleaved-caspase3 were determined by western blotting and quantified. The data are presented as dot plots from three independent experiments. Significant differences among different groups are indicated as *p < 0.05 vs. control; **p<0.01 vs. control; ***p<0.001 vs. control; ****p<0.0001 vs. control.