GSE induced pan-caspase-based apoptosis in Ca9-22 cells. Cells were treated with indicated GSE concentrations (0–400 μg/ml) for 24 h. (A) Histograms of representative pan-caspase activity profile in GSE-treated Ca9-22 cells. Caspase positive % was indicated in the right gated region of each panel. (B) Quantitative analysis for the pan-caspase positive (%). Data, mean ± SD (n = 3). Treatments with the same capital letter are nonsignificant.