CDO1 (cysteine dioxygenase type 1) is a key enzyme that catalyzes the oxidation of cysteine to cysteine sulfinic acid, representing the rate-limiting step in the catabolic pathway converting cysteine to taurine 1. The enzyme requires molecular oxygen and metal cofactors including zinc, iron, and nickel for its catalytic activity. CDO1 expression is tissue-specific, with significant expression in osteolineage cells where it drives taurine biosynthesis 2. The enzyme's activity is tightly regulated through post-translational mechanisms, particularly by LRRC58-mediated ubiquitin-proteasome degradation, which responds to cellular cysteine levels 1. CDO1 has emerged as clinically significant across multiple diseases. In acute myeloid leukemia, CDO1-derived taurine from bone marrow stromal cells promotes leukemogenesis by enhancing glycolysis through mTOR activation 2. In hepatocellular carcinoma, CDO1 functions as a tumor suppressor by regulating glutathione synthesis and ferroptotic cell death, with its degradation by TRIM47 promoting cancer progression 3. Additionally, CDO1 promoter hypermethylation serves as a prognostic biomarker in various cancers, including extrahepatic cholangiocarcinoma and esophageal squamous cell carcinoma, where hypermethylation correlates with poor patient outcomes 45. These findings establish CDO1 as a critical metabolic regulator with significant therapeutic potential.