Figure 6.

Mutations in the Gfi1b promoter that delete Gfi1b-binding sites abrogate repression by Gfi1b. (a) Schematic description of the Gfi1b core promoter luciferase reporter plasmids and the mutations that have been introduced. The sequence represents the tandem promoter binding site shown in Figure 4 (b) Gfi1b core promoter driven luciferase constructs and a construct carrying the mutations indicated in (a) were cotransfected into NIH3T3 cells with pCDNA3 as control (vector) and pCDNA3-expression plasmids for full-length Gfi1b as indicated. The pGl3-promoter vector (left) served as a control. Fold inductions were derived by dividing the normalized luciferase activity of each value by the average of the vector control.