FIGURE 10.

Effect of B-MYB on p53-induced apoptosis and cell cycle arrest. A, effect of B-MYB on p53-induced apoptosis. MCF7 cells were transiently transfected with 0.8 μg (upper) or increasing amounts (0.2 and 0.4 μg, lower) of the indicated expression vectors for wild-type (WT) and deletion mutants (DBD, 373/468, TA, and R1) of B-MYB and 200 nm B-MYB-specific (B-myb) or control scrambled (Sc) siRNAs, together with 0.5 μg of p53 and 1 μg of GFP, in the presence (black bars) or absence (white bars) of 0.38 mm 5-FU. Apoptotic cell death was determined using the GFP expression system. B, effect of B-MYB on p53-induced cell cycle arrest. Transfected MCF7 cells, as described above in A, were treated with doxorubicin (100 ng/ml) for 24 h. The indicated percentages represent the cells in G₀/G₁ (white bars) and G₂/M (black bars) arrest. As a negative control, MCF7 cells expressing pFLAG-CMV-2 empty vector that were not transfected with p53 are indicated (first lanes). The expression level of FLAG-tagged wild-type B-MYB and its deletion mutants was determined by anti-FLAG antibody immunoblot.