Expression of CDKN2B is decreased in response to hypoxia. A-B) U2OS cells were cultured at normoxia (21% O2) or at hypoxia (1% O2) for the time points indicated, and immunoblotting for CDKN2B (A) as well as qRT-PCR analyses for CDKN2B (B) and PGK-1 (C) were performed. Immunoblotting for the housekeeping protein beta-actin was used as a loading control (A). The qRT-PCR values were normalized to the expression of the housekeeping gene HPRT-1, and are shown as average of relative fold change +/− stdev, three independent experiments performed in duplicates (B and C). Statistical analyses: (B) ANOVA (Bonferroni); (C) ANOVA (Dunnett’s T3); ***p ≤ 0.001, *P ≤ 0.05, ns: non significant.