Fig. 4. Effect of CK2 inhibitors on p53 transcriptional activity in HepG2 cells. Cells were incubated for 16 hours under normoxia or hypoxia in the presence or the absence of different concentrations of DRB (µM), 20 µM apigenin (API) or 10 µM TBB. (A) Cells were cotransfected with pG13-Luc and pRL plasmids. p53 activity is expressed as the ratio of native firefly luciferase to synthetic Renilla luciferase activity (means ± 1 s.d.; n=3). (B) Real-time PCR analysis of the p21 mRNA level. Relative p21 mRNA levels were calculated as the ratio of p21 expression in hypoxia-incubated cells to these in control normoxic cells, both normalised to -tubulin levels. (C) Total cell lysates were tested for p21 and -tubulin protein expression by western blotting.