Acts as a transcriptional repressor (PubMed:14550261, PubMed:19409814, PubMed:31587868). Plays a role as a transcriptional corepressor of the Notch-mediated signaling required for T-cell development (PubMed:19409814). Also involved in the TNF and IL-1 induced NF-kappa-B activation. Associates with chromatin at the Notch- regulated SKP2 promoter. {ECO:0000269|PubMed:14550261, ECO:0000269|PubMed:19409814, ECO:0000269|PubMed:31587868}. This is the function of NKAP (NFKB activating protein, Ensembl gene identifier ENSG00000101882).