Fig. 7. The effect of competition by HIF-1 or ARNT with HIF-1Z upon HIF-1 activity. pHIF-1 (A) and pARNT (B) plasmids were cotransfected with the Epo enhancer reporter vector into the stable transfectant cell line of pHIF-1Z. After 16 hours of hypoxia, the luciferase activities of the reporter gene were measured. Each bar, in arbitrary units, represents the mean±s.d. of six experiments, and the loading amount of the plasmid is indicated below the corresponding result. *P<0.05 vs the normoxic control in each condition by using unpaired Student’s t-test.