NFKBI, or Nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha, is a human gene encoded by NFKBIA. It may also be known as: NF-kappa-B inhibitor alpha; I-kappa-B-alpha; IkB-alpha; IkappaBalpha; Major histocompatibility complex enhancer-binding protein MAD3; IKBA; MAD-3. The encoded protein has an amino acid length of 317 and a mass of 35.6 kDa. Other isoforms may exist. NFKBI is a member of the NF-kappa-B inhibitor family. Homologs of this gene exist in other organisms, including: Frog.