Purity ~62% (SDS-PAGE, Coomassie blue staining). Ikba is a cellular protein that inhibits the transcription factor NF-kB. NF-kB plays a central role in cellular stress and inflammatory responses by controlling cytokine-inducible gene expression and lymphocyte stimulation by antigens. In non-stimulated cells NF-kB is sequestered in the cytoplasm via the inhibitory protein Ikba, which obscures the nuclear localization signal of NF-kB and also blocks its ability to bind DNA. In response to various stimuli, including viral infection, ultraviolet radiation and inflammatory cytokines, Ikba is phosphorylated by the protein kinase complex IKK, which triggers its rapid degradation by ubiquitin mediated proteolysis. The liberated NF-kB then translocates to the nucleus and activates the expression of target genes. Mutations in the gene for Ikba result in the functional impairment of NF-kB which causes a decreased production of proinflammatory cytokines and certain interferons, rendering patients