Effect of compression stimulus on HAS gene expression by synoviocytes. Messenger RNA expression levels of HAS-1, HAS-2 and HAS-3 were analysed with real-time RT-PCR. All mRNA of HAS genes were normalized by GAPDH, a housekeeping gene. Data are shown as mean ± SEM., n = 3. *, **, Significant difference from without compression (0 h) at P < 0.05 and 0.01, respectively