Inhibitor of nuclear factor kappa-B kinase subunit alpha (IKK-α) also known as IKK1 or conserved helix-loop-helix ubiquitous kinase (CHUK) is a protein kinase that in humans is encoded by the CHUK gene. IKK-α is part of the IκB kinase complex that plays an important role in regulating the NF-κB transcription factor. However, IKK-α has many additional cellular targets, and is thought to function independently of the NF-κB pathway to regulate epidermal differentiation. IKK-α is a member of the serine/threonine protein kinase family and forms a complex in the cell with IKK-β and NEMO. IKK-α has been shown to function in epidermal differentiation independently of the NF-κB pathway. The zebrafish homolog of IKK-α has also been shown to play a role in the differentiation of the embryonic epithelium. IκB kinase α (IKKα) is a regulator of keratinocyte terminal differentiation and proliferation and plays a role in skin cancer.