The IκB kinase (IKK) is an enzyme complex that is involved in propagating the cellular response to inflammation. This enzyme belongs to the family of transferases, specifically those transferring a phosphate group to the sidechain oxygen atom of serine or threonine residues in proteins (protein-serine/threonine kinases). The systematic name of this enzyme class is ATP.The IκB kinase enzyme complex is part of the upstream NF-κB signal transduction cascade. The IκBα (inhibitor of kappa B) protein inactivates the NF-κB transcription factor by masking the nuclear localization signals (NLS) of NF-κB proteins and keeping them sequestered in an inactive state in the cytoplasm. Specifically, IKK phosphorylates the inhibitory IκBα protein. This phosphorylation results in the dissociation of IκBα from NF-κB. NF-κB, which is now free migrates into the nucleus and activates the expression of at least 150 genes; some of which are anti-apoptotic. The IκB kinase complex is composed of three subunits each encoded by a separate gene: IKK-α (also known as IKK1) (CHUK),IKK-β (also known as IKK2) (IKBKB),IKK-γ (also known as NEMO) (IKBKG). This enzyme participates in 15 pathways related to metabolism: MapK signaling, apoptosis, Toll-like receptor signaling, T-cell receptor signaling, B-cell receptor signaling, insulin signaling, adipokine signaling, Type 2 diabetes mellitus, epithelial cell signaling in helicobacter pylori, pancreatic cancer, prostate cancer, chronic myeloid leukemia, acute myeloid leukemia, and small cell lung cancer.