Effect of saikosaponin-d and radiation on the p53 levels and the bcl2/BAX ratio in SMMC-7721 human hepatocellular carcinoma cells under oxia and hypoxia. A. Western blot analysis of p53, Bax, and Bcl-2 levels under oxia and hypoxia. B. Relative expression of p53. C. Change of Bax/Bcl-2 ratio. SSd: saikosaponin-d; IR: radiation; *p < 0.05, ** p < 0.01 vs. control.