Vincristine induces the S-phase cell cycle arrest by flow cytometry. HepG2.2.15 (4 × 105/well) and HepG2-HBV1.1 (6 × 105/well) cells were treated with vincristine at a concentration of 0.1 μmol/L for 24 h, and the medium was then changed to drug-free culture medium. A: The ratio of the cells in S-phase to G2-phase after vincristine treatment was calculated. The cells were harvested 12, 24, 48, and 72 h after vincristine treatment, respectively; B: Vincristine significantly increased the number of S-phase cells. The cells were harvested 48 h after vincristine treatment. Values represent the mean ± SD of 3 independent experiments. bP < 0.01 vs control group (no vincristine).