Multifunctional nucleolar protein that terminates ribosomal gene transcription, mediates replication fork arrest and regulates RNA polymerase I transcription on chromatin (PubMed:7720715, PubMed:9267035, PubMed:15292447, PubMed:9049305). Plays a dual role in rDNA regulation, being involved in both activation and silencing of rDNA transcription (PubMed:15292447, PubMed:20513429). Interaction with BAZ2A/TIP5 recovers DNA-binding activity (PubMed:15292447). Oligomer. The oligomeric structure enables to interact simultaneously with two separate DNA fragments (PubMed:9092622). Interacts with BAZ2A/TIP5 (PubMed:15292447). Interacts with CAVIN1 (PubMed:9582279, PubMed:27528195). Interacts (via the N-terminal region (NRD) and a C-terminal region) with CDKN2A/ARF; the interaction is direct (PubMed:20513429). Interacts (via C-terminal region) with NPM1/B23 (PubMed:20513429). May be localized to the nucleolus in an NPM1/B23-dependent manner (PubMed:20513429). May be displaced from the nucleolus into the nucleoplasm in an CDKN2A/ARF-dependent manner (PubMed:20513429). May shuttle back and forth from nucleoplasm to nucleolus (PubMed:20513429). The N-terminal region (NRD) inhibits DNA-binding via its interaction with the C-terminal region.