Overexpression of duDDX1 stimulates IFN-β expression. A dual luciferase reporter gene assay was used to study the IFN-β signaling pathway. PcDNA3.0-duDDX1-Flag or empty vector (500 ng/well) were co-transfected with reporter plasmids (100 ng/well) (A) pGL3-IFN-β; (B) pGL3-IRF-7; (C) pGL-NF-κB with pRL-TK (normalization) (50 ng/well). After 24, 36, and 48 hpt, cells were harvested, and luciferase activity was measured. Relative IFN-β-, IRF-7-, or NF-κB-reporter activation was calculated as fold-change in normalized Firefly luciferase activity with reference to mean control values set to 1. Data were means from three independent experiments and each experiment was analyzed in tri plicate. A student t test was performed to assess the difference. * P < 0.05; ** P < 0.01; *** P < 0.001.