Effect of sodium ferulate on the apoptosis rate of IL-1β-induced rat osteoarthritis chondrocytes. Chondrocytes were incubated with sodium ferulate (SF) alone for 24 hours, and then co-treated with IL-1β and SF for 48 hours. After staining with annexin-V-fluorescein isothiocyanate and propidium iodide, chondrocytes were measured on flow cytometry and analyzed with Multi-cycle software (Phoenix Flow Systems, San Diego, CA, USA). Results expressed as percentage of apoptotic cells. Values represent mean ± standard error of the mean of four different simples. **P < 0.01 versus normal control. ##P < 0.01 versus osteoarthritis model control.