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. 2005 Sep;54(9):1309–1317. doi: 10.1136/gut.2005.065086

Figure 6.

Figure 6

 Identification of a region conferring inducible activity via cAMP response element binding protein (CREB), protein kinase A (PKA), and the exogenous PKA activator forskolin. (A) Deletion constructs 1–5 (see fig 2A ▶) were cotransfected in Huh7 hepatoma cells with 50 ng CREB-plasmid and/or 1 µg PKA expression plasmid, as indicated. Construct 1 conferred the highest basal activity (as expected from figs 3 ▶–5 ▶). Luciferase expression was highly induced by cotransfection of CREB and even further enhanced by PKA in all constructs. However, the highest relative induction was seen in constructs 2 and 3 whereas this inducible activity was remarkably lower in constructs 4 and 5. Constructs 1–3 contain a putative Ets-1 binding motif, which was not present in constructs 4 and 5. (B) Forskolin is a chemical inductor of PKA/CREB signalling pathways. Construct 3 was either cotransfected with PKA and/or cells were stimulated with 10 µM forskolin, as indicated. Stimulation with forskolin resulted in maximal activation of relative luciferase expression.