AIM:ToexploretheeffectofcelastrolonapoptosisofSaos-2cellsanditsmechanism.METH-ODS:Saos-2 cells were treated with various concentrations of celastrol , and the cell viability was measured by MTT assay . Apoptosis and reactive oxygen species ( ROS) production were determined by flow cytometry .The protein levels of cleaved caspase-9, cleaved caspase-3 and phosphorylated JNK were evaluated by Western blot .RESULTS:The viability of Saos-2 cells was significantly inhibited by celastrol .Celastrol significantly induced apoptosis of Saos-2 cells.Celastrol signifi-cantly induced ROS production in the Saos-2 cells.Western blot analysis demonstrated that celastrol significantly increased the protein levels of cleaved caspase-9, cleaved caspase-3 and phosphorylated JNK in the Saos-2 cells.CONCLUSION:Celastrol induces caspase-dependent apoptosis through ROS/JNK pathway in Saos-2 cells.