N-TADs of HIF1α or HIF2α is required for its functional interaction with STAT3 or USF2 to activate HIF1 or HIF2 target gene promoter.

<p><b>A</b>) Schematic presentation of HIF1αDPA (Double Proline to Alanine), HIF2αDPA and HIF1α/HIF2α hybrid constructs. <b>B</b>) Western blot analysis of HIF1α, HIF2α, HIF hybrids and STAT3 to monitor the protein expression during CA9/Luc reporter gene assays. <b>C</b>) Activation of HIF1 target gene reporter, CA9/Luc, by the indicated plasmids. HIS is an empty vector that contains a histidine tag only. <b>D</b>) Western blot analysis of HIF1α, HIF2α, HIF hybrids and USF2 to monitor the protein expression during PAI1/Luc reporter gene assays. <b>E</b>) Activation of HIF2 target gene reporter, PAI1/Luc, by the indicated plasmids.