Nuclear factor kappa B (NF-kappaB) is a ubiquitous transcription factor and an essential mediator of gene expression during activation of immune and inflammatory responses. NF-kappaB mediates the expression of a great variety of genes in response to extracellular stimuli including IL-1, TNFa, and bacteria product LPS. NF-kappaB is associated with IkappaB proteins in the cell cytoplasm, which inhibit NF-kappaB activity. The long-sought IkappaB kinase (IKK), which phosphorylates IkappaB, and mediates IkappaB degradation and NF-kappaB activation, was recently identified by several laboratories. IKK is a serine protein kinase, and the IKK complex contains alpha and beta subunits (IKKalpha and IKKbeta). IKKalpha and IKKbeta interact with each other and both are essential for the NF-kappaB activation. IKKalpha specifically phosphorylates IkB-alpha. IKKalpha is expressed in variety of human tissues.