a protein of the NF-kappa-B inhibitor family. Inhibits NF-kappa-B by complexing with and trapping it in the cytoplasm. However, the unphosphorylated form resynthesized after cell stimulation is able to bind NF-kappa-B allowing its transport to the nucleus and protecting it to further IKBA- dependent inactivation. Association with inhibitor kappa B- interacting Ras-like proteins 1 and 2 may also explain the slower degradation. Interacts with ligand-binding domain of thyroid hormone receptor-beta, inhibitor kappa B-interacting Ras-like protein 1, inhibitor kappa B-interacting protein Ras2, p65 (RELA) and c-Rel. Expressed in all tissues examined. Note: This description may include information from UniProtKB.