May be required to maintain the proliferative capacity of stem cells. Stabilizes MDM2 by preventing its ubiquitination, and hence proteasomal degradation (By similarity). Interacts with MDM2; this interaction stabilizes MDM2. Interaction with MDM2 occurs in the nucleoplasm and is triggered by a nucleolar release mechanism, such as mitosis-induced nucleolar disassembly (By similarity). Indirectly interacts with TP53, via MDM2-binding (By similarity). Shuttles between the nucleus and nucleolus. Increased levels in lung tissue in cancer patients. The basic domain (B) allows nucleolar localization in the absence of GTP. The intermediate domain (I) inhibits nucleolar localization by the B domain and is required for exit from the nucleolus. Exit from the nucleolus to the nucleoplasm requires both the I and the acidic (A) domains, and may be triggered by GTP hydrolysis (By similarity). 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.