FIG. 4.

K-bZIP activates ifn-β gene expression in the presence of dominant negative forms of IRF-3 and IKBα. (A) 293T cells were transfected with TBK-1 or HA-K8 expression vectors in the absence of in the presence of increasing quantities of a plasmid coding for a dominant negative form of IRF-3. (B) 293T cells were transfected with IKKβ or HA-K8 expression vectors in the absence or in the presence of increasing quantities of a plasmid coding for a dominant negative form of IκBα. Twenty-four hours later, cells were resuspended in lysis buffer, and luciferase activity was determined using a luminometer. Results are expressed as mean (triplicate) induction (n-fold) of IFN-β luciferase (luc) activity ± SD relative to cells transfected with a control plasmid and are representative of three independent experiments. *, P < 0.05.