Fig. 4

Caspase-3, − 8, and − 9 are involvement in CPT-induced OS cell apoptosis. a The expressions of apoptosis-related proteins were measured by western blotting in OS cells following 20 μM CPT treatment for 24 h. b OS cells were pretreated with Z-VAD-FMK (20 μM) for 1 h and incubated with 20 μM CPT for 24 h. Annexin V/PI analysis was used to detect apoptotic cells by flow cytometry followed by CPT treatment. The respective cell percentages in early and late apoptosis for different dose treatment are presented in the quantitative analysis. The results were expressed as the means ± SD from three independent experiments. **P < 0.01, significantly different compared with control