GAG depletion is dependent on MMP-3 activation. (A) GAG depletion was assessed by 1,9-dimethylene blue assay after treatment for 5 days in the presence of 100 μM XG076. Data are means ± SEM of 3 independent experiments. *P < 0.05, **P < 0.01 vs. corresponding treatment without inhibitor. (B) MMP-13, (C) MMP-3 and (D) ADAMTS-5 mRNA was quantified by real-time PCR after 3 h of treatment with the indicated concentrations of FTY720-P in combination with 10 ng/ml IL-1β or 100 ng/ml TNF-α. Values were normalized to GAPDH and are presented as percentage of gene expression induced by cytokine treatment. Data are means ± SEM of 3 independent experiments. *P < 0.05, ** P < 0.01 versus cytokine treated vehicle control.