Arginase 1 (ARG1) is a manganese-dependent enzyme that catalyzes the final step of the urea cycle, converting L-arginine into L-ornithine and urea. While ARG1 is highly expressed in the liver for ammonia detoxification, it also plays important roles in immune regulation, tissue repair, and disease progression. In myeloid-derived suppressor cells (MDSCs) and M2-like macrophages, ARG1 activity depletes extracellular L-arginine, suppressing T cell proliferation and nitric oxide production. This immunosuppressive function links ARG1 to cancer biology, particularly in hepatocellular carcinoma, pancreatic cancer, and colorectal cancer. ARG1 antibodies are widely used as biomarkers for hepatocellular carcinoma and to study the enzyme’s role in cancer immunology, metabolic disorders, and inflammatory conditions. Catalina offers high-quality, validated ARG1 antibodies that provide sensitivity, specificity, and reproducibility, making them essential tools for research in oncology, immunology, metabolism, and diagnostic pathology.