Transcriptional potential of AML1 mutants.

(A) Transcriptional activities of the AML1 mutants in HeLa cells. Cells were transfected with 5 μg of pM-CSF-R-luc, 3 μg of FLAG-tagged AML1 or AML1 mutant expression vector, 1 μg of the CBFβ expression vector, and 0.25 μg of pRL-tk as an internal control to normalize luciferase activities for transfection efficiency. The levels of expression of CBFβ and AML1 were detected by Western blot analysis with anti-CBFβ antibody (middle) and anti–FLAG M2 antibody (bottom), respectively. (B) Transcriptional activities of the AML1 mutants in U937 cells. Cells were transfected with 2 μg of pM-CSF-R-luc reporter plasmid, an indicated amount of AML1 expression constructs, and 0.2 μg of pRL-tk as an internal control that normalizes luciferase activities for transfection efficiency. The expression vector containing wild-type AML1 (0.2 μg) was cotransfected with increasing doses (0, 0.1, 0.2, and 0.4 μg) of expression vectors containing various AML1 mutants. Each value represents the mean of 3 independent experiments. The error bars indicate the mean ± SD. The numbers of AML1 mutants (1-10) are shown in Figure 1.