The effect of wortmannin and rapamycin on VEGF promoter activity in Ha-ras–transformed cells (NIH3T3R). (A) Wortmannin inhibits the induction of the hypoxia-responsive element in the VEGF promoter in NIH3T3 Ras-transformed cells. Cells that were transiently transfected with 5 μg of a 385-bp VEGF reporter plasmid were preincubated in varying concentrations of wortmannin or rapamycin for 2 hours before hypoxic exposure. Values represent at least five independent transfections. Error bars represent 1 SD of the mean. (B) Wortmannin inhibits the induction of the hypoxia-responsive element in the VEGF promoter in Rat-1 Ras-transformed cells. Transient transfection with 5 μg of the HIF-1 expression vector. Cells were preincubated with varying concentrations of wortmannin for 2 hours before hypoxic exposure. The relative fold induction refers to the ratio of luciferase activity measured in treated cells relative to the activity observed in the untreated controls. Values represent the means of at least three independent transfections. Error bars represent 1 SD of the mean.