Also, the apoptosis in- dex (AI) significantly increased with the concentration gradient compared with that of the control group (Fig. 3). This phenomenon was confirmed by flow cytometry assay. After treatment with 15, 30, and 60 μM lupeol, the apoptotic rates of PCNA-1 cells were 19.15±3.56, 35.87±3.54, and 60.62±2.76 %, respectively, which were all higher than those of PCNA-1 cells cultured under normal conditions (5.45±1.44 %, P