Regulates transcription and acts as corepressor for RBPJ. Recruits RBPJ to the Sin3-histone deacetylase complex (HDAC). Required for RBPJ-mediated repression of transcription (By similarity). May modulate splice site selection during alternative splicing of pre-mRNAs. Interacts with RP9, SNW1, SFRS1, SFRS2,U2AF1, RBPJ, SAP30, HDAC2 NKAP and NEK6. Interacts with Epstein-Barr virus RPMS1. Component of the histone deacetylase complex. Component of the Notch corepressor complex. Interacts with NKAPL (PubMed:25875095). Colocalizes with NEK6 in the centrosome. Phosphorylated by NEK6. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. Contaminating sequence. Potential poly-A sequence.