Figure 4.

Induction of transfected ISG promoter driven reporter genes by IFNs. Cells (5 × 10⁵) in A and B were electroporated with 10 μg of ISG 561-luciferase and ISG 6-16-CAT respectively. IFN-β (150 units/ml) treatment was performed for 18 h. Luciferase and CAT assays were performed by using cell extracts (60 μg) as described. Transfection efficiency was monitored by measuring the expression of cotransfected β-actin-β-galactosidase (3 μg). Experiments in C and D are similar to A and B except that IFN-γ-inducible pIRE-Luciferase and guanylate binding protein-CAT reporter genes were used, respectively. Cells were treated with murine IFN-γ (150 U/ml) for 18 h before the assays.