AQP9 is an aquaglyceroporin that forms homotetrameric transmembrane channels, with each monomer independently mediating glycerol and water transport across the plasma membrane 1. AQP9 exhibits broad substrate specificity, transporting not only water and glycerol but also carbamides, polyols, purines, pyrimidines, lactate, arsenite, and hydrogen peroxide 1. In hepatocytes, AQP9 serves as the primary glycerol uptake route supporting gluconeogenesis and may facilitate urea extrusion. Its lactate permeability suggests involvement in the astrocyte-to-neuron lactate shuttle for neuronal energy supply 1. AQP9 mediates arsenic excretion by the liver, providing partial protection against arsenic toxicity 2. In immune cells, AQP9 is critical for leukocyte migration; AQP9 blockade significantly impairs neutrophil and monocyte motility, particularly under inflammatory conditions 3. AQP9 expression is dysregulated in multiple diseases: upregulated in inflammatory bowel disease and Parkinson's disease with major depressive disorder 45, while its expression and phosphorylation regulate arsenic sensitivity in hepatocellular carcinoma cells 2. These pleiotropic functions position AQP9 as a potential therapeutic target in cancer, inflammatory, and neurodegenerative diseases.