NFKBIE protein expression is up-regulated following NF-?B activation and during myelopoiesis. NFKBIE is able to inhibit NF-?B-directed transactivation via cytoplasmic retention of REL proteins.NFKB1 or NFKB2 is bound to REL, RELA, or RELB to form the NF-?B transcription factor complex. The NFKB complex is inhibited by I-kappa-B proteins (NFKBIA or NFKBIB), which inactivate NF-kappa-B by trapping it in the cytoplasm. Phosphorylation of serine residues on the I-kappa-B proteins by kinases (IKBKA, or IKBKB) marks them for destruction via the ubiquitination pathway, thereby allowing activation of the NF-kappa-B complex.For some genes, activation requires NFKB interaction with other transcription factors, such as STAT (see STAT6), AP-1 (JUN), and NFAT (see NFATC1).