FIG. 2.

Sp1/Sp3 binding sites in the proximal enhancer have positive and synergistic effects on MIE promoter activity. (A) Schematic representation of the structures of the CAT gene constructs. (B) HFF cells were transfected with each plasmid and harvested at 72 h. CAT assays were performed as described in Materials and Methods. Experiments were performed in triplicate. Values represent percent conversion from unacetylated chloramphenicol to the acetylated form. (C) The increase in activation (n-fold) of CAT activity relative to that for pCAT TATA was determined and plotted on the graph. Data represent averages from three independent experiments.