Background：

NF-kappa-B is a ubiquitous transcription factor involved in several biological processes. It is held in the cytoplasm in an inactive state by specific inhibitors. Upon degradation of the inhibitor， NF-kappa-B moves to the nucleus and activates transcription of specific genes. NF-kappa-B is composed of NFKB1 or NFKB2 bound to either REL， RELA， or RELB. The most abundant form of NF-kappa-B is NFKB1 complexed with the product of this gene， RELA. Four transcript variants encoding different isoforms have been found for this gene.