Time course of LPS-induced activation of IKK and IKKβ as compared with that induced by TNF-. (A) LPS-induced phosphorylation of 1μg IκB-GST, IκBβ-GST, and IκBɛ-GST fusion proteins; (B) TNF-–induced phosphorylation of IκB-GST fusion protein. The IKK kinase assay was done as specified in Materials and Methods and the kinase complex was immunoprecipitated with anti-IKK antibody.