IκB kinase β (IKKβ) is a component of a multiprotein kinase complex that regulates the activity of the transcription factor NF- κB. Activation of the IKK complex via upstream stimuli leads to phosphorylation and degradation of NF-κB bound IκB (Inhibitor of κB). Subsequently, free NF-κB dimers enter the nucleus and regulate the transcription of a variety of target genes involved in cell proliferation and differentiation, apoptosis, and inflammation, etc. The IKK complex consists of 2 highly homologous kinase subunits, IKKα and IKKβ, and a nonenzymatic regulatory component, IKKγ/NEMO. The relative contributions of IKKα and IKKβ to the signaling complex vary according to the requirements of the cell. IKKβ plays a predominant role in immune responses, while IKKα alone appears to be sufficient for at least some developmental systems. Recently, IKK/NF-κB signaling pathway was studied as therapeutic targets in cancer.