FIG. 5. .

cEBP-β is a component of the interferon-β (IFN-β)–induced DNA complexes in mutant IFNAR-2c (FF) cells. (A) EMSA analysis was performed using nuclear extracts from wild-type IFNAR-2c (R2C) cells treated for 5 h with IFN-β (5,000 U/mL). Supershift assays were performed using anti-interferon regulatory factor (IRF)-3, 2 different antibodies to STAT1, anti-STAT2, anti-STAT3, anti-STAT5, anti-p65, anti-c-myc, and anti-IRF-1. (B) EMSA analysis was performed using the above extracts as explained in (A) and supershift experiments were done using anti-IRF-1 and anti-C/EBP-β. (C) Overexpression of cEBP-β enhanced IFN-β–induced transcription of IRF-9. FF cells were co-transfected with the wild-type IRF-9 promoter–reporter luciferase construct (wtIRF-9-1050) alone or in combination with wild-type cEBP-β expression vector. Cells were stimulated with and without IFN-β (1,000 U/mL for 16 h). IFN-β stimulation status are indicated as “+” for stimulated cells and “−” for nonstimulation. The luciferase activity was determined and normalized to Renilla luciferase for transfection efficiency. The fold induction with IFN-β compared to untreated control is shown. Results represent an average of 3 experiments with triplicate samples for each treatment.