The regulation of ET-1 promoter by PlGF involves HIF-1αresponse elements. HPMVECs were transfected with indicated wild-type and mutant constructs followed by treatment with PlGF for 6 hours in the absence or presence of pharmacologic inhibitors. (A and B) relative luciferase activity. Data are expressed as means (± SE) of 3 independent experiments. ***P < .001. (C) HIF-1α binding to native chromatin was demonstrated by ChIP assay using HIF-1α or normal rabbit IgG antibodies. The ChIP products were amplified by PCR using primers flanking HIF-1α binding sites in the ET-1 promoter as shown in Table 1. Data are representative of 2 different experiments.