Nuclear factor-κB (NF-κB) represents a family of inducible transcription factors, which regulates a large array of genes involved in different processes of the immune and inflammatory responses.1 This family is composed of five structurally related members, including NF-κB1 (also named p50), NF-κB2 (also named p52), RelA (also named p65), RelB and c-Rel, which mediates transcription of target genes by binding to a specific DNA element, κB enhancer, as various hetero- or homo-dimers.2 The NF-κB proteins are normally sequestered in the cytoplasm by a family of inhibitory proteins, including IκB family members and related proteins characterized by the presence of ankyrin repeats.3 To date, the best studied and most important IκB family member is IκBα. In addition, the precursor proteins of NF-κB1 and NF-κB2, p105 and p100, serve as IκB-like proteins, because their C-terminal potion resembles the structure of IκB and has NF-κB inhibitory functions.
