Distribution of hypoxia inducible factor 1α ( HIF-1α ) mRNA levels in 82 breast tissues determined by real-time quantitative reverse transcription PCR assa y. HIF-1α mRNA levels were expressed in normalised copy numbers (NCN) on the basis of TATA box-binding protein (TPB) gene content of the tissues as described in the Methods section. Patients grouped according to histological type of tissues (x axis). HIF-1α mRNA levels (y axis) were represented according to these different groups of patients. Results were plotted on a logarithmic scale. HIF-1α splice variants were detectable in all samples at varying levels. Splice variant HIF-1α
516mRNAs were expressed at levels 100-fold lower than HIF-1α
TAG. Variant HIF-1α
557mRNAs that were expressed at levels 1,000-fold lower than HIF-1α
TAGare not shown.