Fig 4. Role of IKKα in type I IFN-dependent and independent STAT1 phosphorylation induced by dsRNA.

(A) HeLa cells were transfected with siRNA targeting IKKα or control siRNA for 48 h. Then, the cells were treated with an anti-IFNAR neutralizing antibody for 1 h followed by transfection with poly I:C (50 ng/well) for an additional 4 h. HeLa cells were also treated with IFN-β (200 IU/ml) for 15 min as a control to confirm the neutralizing activity of the anti-IFNAR antibody. (B) IFNAR-null U5A cells were transfected with siRNA targeting IKKα or control siRNA for 48 h, and the cells were then further transfected with poly I:C (500 ng/well) for 10 h. Cell extracts were analyzed by immunoblotting. The results are representative of three independent experiments.