A, VEGFR2 staining in the tumor rim and center. A, VEGFR2 staining in the tumor rim and center. B, human VEGF plasma levels of sacrificed A2780-bearing animals. C, tumor proliferation rate at the tumor rim and center. After 7 days of sunitinib overall tumor proliferation decreases, though it remains high at the rim. D, tumor HIF1α expression is high after 1 and 2 weeks of sunitinib treatment. After the stop week, HIF1α decreases towards baseline. *, P < 0.05; **, P < 0.01. Data presented as SEM. Wouter B. Nagengast et al. Cancer Res 2011;71:143-153 ©2011 by American Association for Cancer Research