Nuclear factor kappa B (NF-κB) is a ubiquitous transcription factor and an essential mediator of gene expression during activation of immune and inflammatory responses. NF-κB mediates the expression of a great variety of genes in response to extracellular stimuli including IL-1, TNFα, LPS and mitogens. A serine/threonine protein kinase which mediates NF-κB activation by IL-1, TNFα and CD95 was identified recently and designated NIK (for NF-κB inducing kinase). NIK is an activator of IκB kinase alpha and beta (IKKα and IKKβ). Therefore, NIK is a key molecule in the NF-κB signaling pathway leading to the induction of a variety of gene expression in response to proinflammatory cytokines and bacteria products.
