Localization of the negative response element. (A) The 2 fragments spanning +63 to +121 of the first exon of the VWF gene cloned upstream of the SV40 promoter and luciferase reporter gene. Mean normalized luciferase expression relative to a “No insert” control pGL2 construct is graphed as a percentage. The number (n) of experiments carried out is indicated on each graph. The error bars indicate the standard error of the mean. Statistical differences between each deletion construct and the pGL2 control construct were assessed using a Student t test, and a P value of less than .05 is considered significant. (B) A diagrammatic representation of the nucleotide sequences included in the constructs tested in panel A. The VWF E4BP4 binding element is shown.