(a) DAPI and Hoechst staining of U2OS and SaOS-2 cells treated with different concentrations of oleandrin; Bar scale: 30 μm; (b) The apoptosis of U2OS cells treated with different concentrations of oleandrin that detected by flow cytometry (FCM); (c) Statistical analysis of the total apoptosis rate of U2OS cells followed by FCM detection; n = 3, Mean ± SEM; ** p < 0.01, *** p < 0.001, vs. control (0 nM) group; (d) The apoptosis of SaOS-2 cells treated with different concentrations of oleandrin that detected by FCM; and (e) Statistical analysis of the total apoptosis rate of SaOS-2 cells followed by FCM detection; n = 3, Mean ± SEM; ** p < 0.01, *** p < 0.001, vs. control (0 nM) group.