UCKL1 (uridine-cytidine kinase like 1) is a pyrimidine salvage pathway enzyme that phosphorylates uridine and cytidine to UMP and CMP with catalytic efficiency of 1.2 × 10⁴ s⁻¹ M⁻¹ for uridine 1. Beyond its canonical metabolic function, UCKL1 exhibits critical non-canonical roles in disease pathology. In cardiac fibrosis, UCKL1 forms an obligate functional complex with UCK2 that acts as a molecular scaffold recruiting E3 ubiquitin ligase TRIM21 to degrade Smurf2, thereby amplifying pro-fibrotic TGF-β signaling and myofibroblast differentiation after myocardial infarction 2. In colorectal cancer, UCKL1 represses ferroptosis through a non-metabolic mechanism involving Nrf2 stabilization and subsequent SLC7A11 upregulation, with UCKL1 depletion sensitizing cells to GPX4 inhibitors 3. UCKL1 is significantly upregulated across multiple cancers including hepatocellular carcinoma, prostate cancer, and glioblastoma 456. In tumor biology, UCKL1 downregulation decreases proliferation, enhances apoptosis, increases natural killer cell-mediated cytolysis, and reduces metastasis 71. These findings identify UCKL1 as a druggable target with therapeutic potential in cancer and cardiac disease.