Intended Use: The Phospho-IKKa/b (Ser176/180) Antibody Sampler Kit contains reagents to examine protein levels of IKKa when phosphorylated at Ser176/180 and IKKb when phosphorylated at Ser177/181. The kit contains primary and secondary antibodies to perform four Western Blots with each antibody. Background: The NF-κB/Rel transcription factors are present in the cytosol in an inactive state, complexed with the inhibitory IκB proteins (1-3). Most agents that activate NF-κB do so through a common pathway based on phosphorylation-induced, proteasome-mediated degrada- tion of IκB (3-7). The key regulatory step in this pathway involves activation of a high molecular weight IκB kinase (IKK) complex, whose catalysis is generally carried out by three tightly associated IKK subunits. IKKa and IKKb serve as the catalytic subunits of the kinase. IKKγ serves as the regulatory subunit (8-9). Activation of IKK depends on phosphorylation; Ser177 and Ser181 in the ac