Reduction of VWF promoter activity by mutation of the CCAAT element.

(A) A schematic representation of the plasmids HGH-K and K-NFY, with the base substitutions in the CCAAT element shown in italics. (B) BAE cells were stably transfected with a mixture of each VWF-HGH test plasmid and a plasmid containing the neomycin resistance gene. Transfected cells were continuously grown in the presence of the neomycin analogue G418 to select for stably transfected cells, and cells in the culture dish were allowed to reach confluency to obtain a heterogeneous population of stably transfected cells. Growth hormone expression from confluent plates was determined and normalized to the cell number. The results shown are the average of 2 independent transfections for each plasmid and the error bar represents the standard deviation. The statistical analysis demonstrated that theP value was less than .01. The average level of growth hormone expression from HGH-K plasmid in heterogeneous cell populations was determined to be 60 ng/mL per 100 000 cells.