Induction of IKKβ activation by plasmin.

(A) Kinetic study of IKKβ activation. Monocytes were either unstimulated or stimulated with plasmin 0.43 CTA U/mL for the indicated times. IKKβ was precipitated from the cell extracts with a specific rabbit anti-IKKβ antibody and protein A–agarose. In vitro kinase assays (KA) were performed using IκBα-tagged fusion protein corresponding to the full-length human IκBα (amino acids 1-317) as a substrate. Composition of the immunoprecipitates was analyzed by immunoblot with mouse anti-IKKβ (IB). Results of 1 of 3 experiments are shown. (B) Monocytes were incubated with or without plasmin 0.43 CTA U/mL or LPS 1 μg/mL for 10 minutes. IKKβ was immunoprecipitated with a specific rabbit anti-IKKβ antibody. Precipitates were analyzed for kinase activity (KA). Phosphorylated substrate was visualized by autoradiography and quantified densitometrically. *P < .05 and **P < .01 versus unstimulated controls. Results are the mean ± SEM of 3 independent experiments.