Chondroitin sulfate-dependent increase of TNFα-induced protein and correlation with the decrease in matrix metalloproteinase activation. The chondroitin sulfate (CS)-dependent increase of TNFα-induced protein (TSG6 or TNFAIP6), and its correlation with the decrease in matrix metalloproteinase activation. Overexpression values of TSG6 were determined by (A) real-time PCR and (B) western blot analysis of IL-1β-stimulated human articular chondrocyte secretomes as described in Materials and methods. The CS-mediated decrease of MMP1 and MMP3 activation was confirmed by western blot analysis (B). Each condition was tested in duplicate. Results are expressed as the mean ± standard error of the mean of three independent experiments. Representative images of the western blot assays are shown. *P < 0.05, CS-treated group was significantly different from IL-1β-stimulated group.