NF-kB is silenced in the cytoplasm by an inhibitory protein, IkB. IkB proteins are phosphorylated by IkB kinase complex consisting of at least three proteins, IKK1/α, IKK2/β, and IKK3/g. External stimuli such TNF-α or other cytokines results in phosphorylation and degradation of IkB releasing NF-kB dimers. NF-kB dimer subsequently translocates to the nucleus and activates target genes.
