NF-kappa-B inhibitor delta, also known as NFKBID, is a member of the IkB family of proteins can be divided into four groups (IkB-alpha, IkB-beta, IkB-gamma, IkB-epsilon). NFKBID plays a role in the regulation of both inflammatory responses and cytokine, IL-2 and IL-6 expression via NFkB activity. Existing as three alternatively spliced isoforms, NFKBID associates with RelB, NFkB p50 and NFkB p65 in nucleus, and is thought to assist in thymocyte selection in response to TCR induction. Recombinant human NFKBID protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.