FIGURE 3.

Mutagenesis analysis of the GADD45α promoter demonstrates the importance of the CCAAT-BP, NF-Y, in its up-regulation after iron depletion. This interaction receives stabilization by v-MYB and is enhanced by CEBPα. A, diagram illustrating a section of the wild-type GADD45α promoter region with the consensus sequences for a number of transcription factors potentially involved in its activation. B, diagram showing a section of the GADD45α promoter region with mutations in the consensus sequences for a number of transcription factors. C, schematic demonstrating the wild-type and mutated consensus sequences that are part of the luciferase promoter constructs. These constructs were assessed after transient transfection of MCF7 cells, which were then incubated with control medium, or this medium containing 311 (25 μm) or DFO (150 μm) for 24 h/37 °C. The activity of the promoter constructs is given as raw light units (RLU)/μg of protein. Results are typical of three experiments and are given as mean ± S.D. (***, p < 0.001.)