The IkappaB-Kinase (IKK) complex is a multisubunit protein complex crucial for signal-induced phosphorylation of the IkappaB proteins and thus controls the activity of the transcription factor NF-kappaB. Besides the two kinases IKKalpha and IKKbeta, the IKK complex contains NEMO/IKKgamma, an additional subunit with regulatory and adaptor functions.