Effect of Glc, GlcN-S, GlcA and GlcN-HCl on the mRNA expression of proteinases [MMP-3 (A), -13 (B)]. Confluent human chondrocytes in 25-cm3 flasks were cultured with IL-1β (10 ng/ml) in the presence and absence of each chemical for 24 hours. Cells were harvested and gene expression was analyzed. MMP, matrix metalloproteinase. *, ** Denotes a value that is significantly different (p < 0.05 and p < 0.01, respectively) from the IL-1β control.