Figure 2

Chronic blockade of secreted VEGF induces a resistance to apoptosis. (A, B) Spontaneous and hypoxia-induced apoptosis. Cells that were treated without (none) or with an unimmunized IgG or an anti-VEGF mAb for 2 or 60 days were exposed to normoxia or hypoxia (~0.1% O₂) for 3 days, then apoptotic cells were determined by TUNEL assay (n=5, means ± S.D.). (C, D) Effect of VEGFR-TKI or knockdown of Vegf mRNA on hypoxia-induced apoptosis in the mAb-long cells. Cells were untreated (none) or treated with VEGFR-TKI, or transfected with the indicated siRNA, or both for 3 days under hypoxic conditions. Then, apoptotic cells were determined by TUNEL assay. *P < 0.01., compared with the respective untreated control cells (none) (n=5, means ± S.D.).