The protein encoded by this gene belongs to the NF-kappa-B inhibitor family, which inhibit NF-kappa-B by complexing with, and trapping it in the cytoplasm. Phosphorylation of serine residues on these proteins by kinases marks them for destruction via the ubiquitination pathway, thereby allowing activation of the NF-kappa-B, which translocates to the nucleus to function as a transcription factor.