Pro inflammatory cytokines activate the transcription factor NF kappa B by stimulating the activity of a protein kinase that phosphorylates Ikappa B, an inhibitor of NF kappa B, at sites that trigger its ubiquitination and degradation. A large, cytokine responsive Ikappa B kinase (IKK) complex has been purified and the genes encoding 2 of its subunits have been cloned. These subunits, IKK alpha and Ikk beta, are protein kinases whose function is needed for NF kappa B activation by pro inflam