Identification of the VEGF-responsive region within the TF promoter. Reporter plasmids used in this study are shown schematically (see also Materials and Methods). Luciferase activity of reporter constructs transiently transfected in HUVEC in the absence (A) or presence (B) of VEGF was calculated relative to wild-type (wt) promoter activity designated as 100%. In each experiment values were determined from duplicate wells and normalized for transfection efficiency. Results from three independent experiments are shown as mean values ± SD. *P < .01 versus wt activity.