UCK2 (uridine-cytidine kinase 2) is a pyrimidine salvage pathway enzyme that phosphorylates uridine and cytidine to their monophosphate forms, utilizing ATP or GTP as phosphate donors 12. The enzyme also phosphorylates various nucleoside analogs including 5-fluorouridine and 5-fluorocytidine 1, making it relevant for antiviral and anticancer therapy. UCK2 functions as a rate-limiting enzyme in pyrimidine salvage 3. mTORC1 regulates UCK2 protein stability through the CTLH-WDR26 E3 ligase complex 3, while GART protects UCK2 stability under glucose limitation via AMPK-mediated signaling 4. Notably, UCK2 exhibits non-canonical, metabolism-independent functions: it forms a complex with UCKL1 that acts as a molecular scaffold to regulate TGF-β signaling in cardiac fibrosis 5. Clinically, UCK2 is significantly upregulated in hepatocellular carcinoma (HCC) and bladder cancer, correlating with poor prognosis, advanced tumor stage, and immunotherapy response 67. UCK2 modulates immune microenvironments through M2-macrophage polarization in HCC 6 and regulates PI3K/AKT/mTOR signaling in bladder cancer 7. These findings position UCK2 as a potential therapeutic target for metabolic reprogramming in cancer.