IKKα (IkB kinase-α or IKK-1) is part of a large protein complex responsible for the inducible phosphorylation of IkB proteins. Human IKK-α is an 85 kDa peptide that has been shown to activate NFkB by phosphorylation of IkB proteins. IKKα interacts with its upstream kinase, NIK, and its downstream substrate, the IkB proteins. Mutations of IKKα in its kinase domain lead to a dominant-negative phenotype that suppresses TNF-α and IL-1β induced NFkB activation.