FIG. 9.

Cooperative effect of SCL and LMO1 on E-box-mediated transcription. (A) NIH 3T3 cells were transfected with the indicated constructs in triplicate, along with an internal transfection control (pCAT Control; Promega); 5 μg of all expression vectors was used unless otherwise indicated. The values presented are the means ± the standard deviation of relative luciferase units, divided by the counts per minute (CAT activity) to control for transfection efficiency; in some cases, the standard deviation bars are too small to be seen. The data are plotted on a logarithmic scale, and the values for each triplicate are shown above the data bars. An asterisk indicates a significant difference (P < 0.001) between the transfections with SCL alone and those with LMO1 and SCL. The entire experiment was repeated once with similar results. (B) The experiment was performed and the data are presented as described for panel A, except that E(5,2)-luc was used as the reporter vector. (C) Expression of CD4 is decreased in thymocytes from SCL LMO1 mice. Ten micrograms of total RNA were assayed for CD4 expression by Northern blotting; actin was used as a loading control. The genotypes are as indicated, and the ratios of CD4 to actin signals are shown below each lane.