Rexpression of Ets-1 could not further upregulate the promoter activity mediated by BORIS, as shown by several repetitions. Surprisingly, co-transfection with an expression plasmid encoding for Sp1 partly repressed the stimulatory effect mediated by BORIS (p = 0.001), whereas the addition of expression plasmid encoding for Ets-1 abrogated this repression (Figure 5B). To verify the repressive effec