Figure 3.

Arnt interacts with the CDKN2B promoter. ChIP experiments were performed on extracts from U2OS cells using an antibody (Ab) against Arnt or preimmune IgG as indicated. The cells were cultured at normoxia (21% O₂) or at hypoxia (1% O₂) for 4 or 24 hours before harvested. qPCR was performed with primers spanning the CDKN2B proximal promoter (−168/-19) (A), primers spanning a distal CDKN2B promoter sequence (−3874/-3744) (B) and primers spanning a hypoxia response element (HRE) of the PGK-1 proximal promoter (−75/+101) (C). The results are given as average enrichment of the indicated promoter fragment +/− stdev, n = 6. Statistical analyses: (A)ANOVA (Dunnett’s T3), (B-C)ANOVA (Bonferroni); **P ≤ 0.01, *P ≤ 0.05, ns: not significant.