Stabilizes TERF1 telomeric association by preventing TERF1 recruitment by PML. Stabilizes TERF1 protein by preventing its ubiquitination and hence proteasomal degradation. Does so by interfering with TERF1-binding to FBXO4 E3 ubiquitin-protein ligase. Required for cell proliferation. By stabilizing TRF1 protein during mitosis, promotes metaphase-to-anaphase transition. Stabilizes MDM2 protein by preventing its ubiquitination, and hence proteasomal degradation. By acting on MDM2, may affect TP53 activity. Required for normal processing of ribosomal pre-rRNA. Binds GTP. Interacts with MDM2; this interaction, which occurs in the nucleoplasm, stabilizes MDM2. Indirectly interacts with TP53, via MDM2-binding. Interacts with TERF1; this interaction probably occurs in the nucleoplasm and is increased during mitosis, when the nucleolus is disassembled. This binding may promote TERF1 homodimerization. Interacts with TERT. Up-regulated during mitosis and down-regulated in the G1 phase. In contrast to other GTP-binding proteins, this family is characterized by a circular permutation of the GTPase motifs described by a G4-G1-G3 pattern. Belongs to the TRAFAC class YlqF/YawG GTPase family.