MPHOSPH10 (M-phase phosphoprotein 10) is a essential nucleolar protein that functions as a core component of the U3 small nucleolar ribonucleoprotein (U3 snoRNP) complex 1. It forms a stable hetero-trimeric complex with Imp3 and Imp4 proteins that assembles into the small subunit (SSU) processome, the initial precursor of eukaryotic ribosomal subunits 2. MPHOSPH10 is required for early cleavage steps during pre-18S ribosomal RNA processing at multiple U3 snoRNA-dependent sites (A0, A1, A2) 3. Its nucleolar localization and delivery of the Mpp10-Imp3-Imp4 complex depend on the protein Sas10, which stabilizes MPHOSPH10 and protects it from degradation 4. Clinically, MPHOSPH10 dysregulation associates with disease pathogenesis. Variants in MPHOSPH10 were identified in patients with early-onset Parkinson's disease through exome sequencing, with an estimated odds ratio of 1.53 5. In breast cancer, MPHOSPH10 was incorporated into an AI-assisted RNA-binding protein signature model that stratified patients into prognostic risk groups, with high MPHOSPH10 expression correlating with elevated tumor mutational burden and immune-suppressive microenvironments 6. Additionally, MPHOSPH10 expression is downregulated under hypoxic conditions in neuroblastoma cells and can be restored by Panax ginseng treatment, suggesting involvement in hypoxia-induced cellular responses 7. Anti-MPHOSPH10 autoantibodies are detected in scleroderma patients with diffuse disease and esophageal/lung involvement, indicating potential autoimmune relevance 8.