Relative expression of MMP-3 (A), TIMP-3 (B), HAS-1 (C), HAS-2 (D), AGG (E) and COL2A1 (F) in all experimental groups. Individual bars show the mean ± SD. A significant differences (p < 0.05) between the four groups at the same condition (48 h non-IL1, 48 h IL1, 72 h non-IL1 and 72 h IL1) is displayed with superscript (a, b) on the bars. A significant difference (p < 0.05) between treatment and non-treatment with IL-1β at the same period (48 or 72 h) is displayed with superscript (*) on the bars. G.1 = control group; G.2 = solution control; G.3 = non-silencing siRNA; and G.4 = MMP-3 siRNA.