GA blocks HIF activity and reduces HIF target expression. GA blocks HIF activity and reduces HIF target expression. A, HEK293T cells were cotransfected with HRE–luciferase and renilla–luciferase plasmids and treated with vehicle or GA in the absence or presence of hypoxia for 24 hours before luciferase activity was measured. *, P < 0.005; **, P < 0.00005 by t test. B, RCC cells were treated with vehicle or GA in the absence or presence of hypoxia for 48 hours and protein expression was measured by immunoblot analysis. Justin M. David et al. Mol Cancer Ther 2014;13:788-799 ©2014 by American Association for Cancer Research