Figure 4: Western blot analysis of the caspase-3 protein activation, Bax, Bcl-2, and Bax : Bcl-2 ratio of Hela cells. Cells were exposed to cisplatin (50, 35, and 30 μM for AD293, Hela, and OVCAR-3 cells, resp.) and cisplatin plus hyperoxic preconditioning (2 h) for 24 h. Each value in the graph represents the mean ± SEM band density ratio for each group. Beta-actin was used as an internal control ().