Expression of VWF promoter fragment with base substitution mutations in endothelial-specific protein-DNA binding site. (A) DNA sequence of the VWF region that forms the endothelial-specific DNA-protein complex with the protein(s) binding site underlined. Arrows show the base substitution mutations that are incorporated into the VWF promoter to generate the HGH-KH plasmid. (B) Growth hormone expression is shown from transiently transfected BAE cells with VWF-HGH plasmid containing no mutation ([HGH-K] wild type), mutation in GCC sequence as shown in panel A, and 2 plasmids with mutations in NFY (HGH-KY) and NF1 (HGH-Krm3) repressor binding sites. For these analyses, 12 independent transfection experiments were carried out for each plasmid. (C) Growth hormone expressions are shown from BAE cells stably transfected with (HGH-K) wild-type and HGH-KH. For these experiments, 36 individual clones of stably transfected cells (G418-resistant clones) were selected for each transfected plasmid, and the results represent the mean value of growth hormone from these clones. Solid triangle labeled M5 represents the 3-base substitution mutation shown in panel A. Open triangles in panels B and C represent mutations in NFY or NF1 binding site. Percentage of growth hormone activities was determined as previously described for transient⁸  and stable transfection.¹²  The error bars represent standard error.