Expression of apoptosis-related genes induced by the generation of oxidative stress under conditions of hypoxia with or without vitamin C. Using real-time quantitative PCR, a significantly increased ratio of BAX/BCL2 mRNA was observed (D). ACTB mRNA was used to normalize the gene expression. The results are expressed as the mean ± SEM. * indicates P < .05, between the samples cultured with and without vitamin C; PCR, polymerase chain reaction; mRNA, messenger RNA; SEM, standard error of the mean.