FIG. 5.

C/EBPβ, depending on its level of expression, activates or represses the albumin promoter in HeLa cells. HeLa cells were transfected with 10 μg of DNA from plasmid pALB (containing the mouse albumin promoter upstream of the CAT gene [25]) together with increasing amounts of CMV-C/EBPβ (as indicated below the bar graphs) and 0.6 μg of RSV/L (18) as an internal control. CAT activities were quantified relative to the activity obtained with pAlb cotransfected with 2.0 μg of pcDNAI, which was set at 0.1. Relative CAT activities were as follows: 0 μg of C/EBPβ, 0.1; 0.25 μg of C/EBPβ, 0.7; 0.3 μg of C/EBPβ, 0.68; 0.5 μg of C/EBPβ, 0.07; 1.0 μg of C/EBPβ, 0.03; 1.5 μg of C/EBPβ, 0.015; and 2.0 μg of C/EBPβ, 0.005.