Figure 2. Repression of p27^kip1 promoter activity by Cux1 and Grg4.

293T cells were transiently transfected with 1 µg of reporter construct containing p27 upstream sequences from −1609 to +178 fused to the luciferase reporter gene (+), together with different concentrations of the Cux1 and Grg4 expression vectors (amounts shown are in µg) or with empty pcDNA3.1 expression vector (amounts shown are in µg). In the presence of Grg4, significantly less Cux1 is required to repress p27 promoter activity (3^rd and 4^th bar). Promoter activity was plotted as fold change, normalized to the expression of a co-transfected renilla expression construct. Activity is expressed as the mean of three separate experiments performed in triplicate. Error bars indicate standard deviation. ANOVA showed a significant reduction in luciferase activity following cotransfection with Grg4 in a dose dependent manner (P< 0.002).