Figure 1.

Time course of hypoxic induction of the VEGF mRNA and determination of VEGF mRNA half-life under normoxia and hypoxia. (A) Northern analysis of total RNA from BALB/c3T3 cells incubated under normoxia (20% O₂) or hypoxia (1% O₂) for the indicated times. The VEGF mRNA was detected by probing with a 529 bp SmaI–BamHI fragment from the VEGF 3′UTR. An oligonucleotide probe specific for 18s rRNA was used as an internal standard. (B) Quantitative analysis of VEGF mRNA stability using pooled data from two independent experiments that used actinomycin D. The VEGF and β-actin mRNAs were detected by RNase protection analysis and quantitated by PhosphorImager analysis. The level of VEGF mRNA was normalized with respect to β-actin mRNA. Open circles represent cells incubated under normoxia; closed circles represent cells incubated under hypoxia. The half-life of the VEGF mRNA was 1.1 h under normoxia and 4.0 h under hypoxia.