FIG. 2.

IKKɛ and TBK-1 can directly phosphorylate VP35 by in vitro kinase assay. In vitro kinase assays were performed with FLAG-tagged kinase, GST, GST-IRF-3-C (amino acids 375 to 427), or FLAG-VP35 serving as a substrate. Proteins were separated by SDS-PAGE, phosphorylation was visualized by autoradiography (A and C), and proteins were visualized by Coomassie blue staining (B and D). FLAG-IKKɛ was used in A and B (lanes 1 to 9), and TBK-1 was used in C and D (lanes 4 to 6). The kinase-inactive forms were used in A and B (lanes 10 and 11) and in C and D (lane 8).