PlGF promotes HIF-1α binding to DNA in vitro and in vivo. (A) EMSA demonstrating binding activity of HIF-1α in THP-1 nuclear extracts to its consensus DNA binding sequence. Where indicated, 50-fold excess of unlabeled probe or antibody to HIF-1α was added. Complex formation was visualized by autoradiography. (B) THP-1 cells were treated with PlGF for 4 hours in the absence and presence of pharmacologic inhibitors. The soluble chromatin was isolated and immunoprecipitated with either antibody to HIF-1α (top panel) or control rabbit IgG (bottom panel). The primers flanking HIF-1α binding sites in the ET-BR promoter as indicated in Table 1 were used to amplify the products by PCR. The bottom panel is amplification of input DNA before immunoprecipitation. Data are representative of 2 independent experiments. Where indicated, the vertical lines show the repositioned gel lanes.