Figure 4.

Role of CRE2, CRE3, and C/EBPβ sites for Star transcription in TG cells. CAT constructs controlled by WT −96Star promoter, or its mutations, were examined in TG cells treated with 8-Br-cAMP as described in Fig. 2. Note that the mutTGA construct specifically targets the C/EBPβ-3 binding site. In addition, WT 96Star was coexpressed in the presence of the dominant-negative mutant protein CREB, ACREB. The activity values (mean ± sd) are presented relative to the activity of −96Star in cAMP treated cells. Activity levels were statistically significant when compared with the respective values obtained for the −96Star construct: a, P < 0.05; b, P < 0.001; c, P > 0.05.