Fig. 2. Effect of CK2 inhibitors on HIF-1 and p53 DNA binding activity in HeLa cells. Cells were incubated for 5 hours under normoxia or hypoxia in the presence or absence of different concentrations (µM) of DRB or apigenin (API). Nuclear extracts were tested for HIF-1 (A) or p53 (B) binding to a specific probe. Results are expressed in absorbance as a percentage of normoxic control (means ± 1 s.d.; A, n=3; B, n=6). ^*P<0.05, ^**P<0.01, ^***P<0.001, NS, not significant vs. normoxia; (^*)P<0.05, (^**)P<0.01, (NS) not significant vs. hypoxia.