The AQP4 protein forms water-specific channels that are critical for brain water homeostasis and lymphoid solute transport. It regulates water exchange at the blood-brain interface, promoting the influx of cerebrospinal fluid into the brain and the drainage of interstitial fluid. AQP4 Protein, Mouse (Cell-Free) is the recombinant mouse-derived AQP4 protein, expressed by E. coli Cell-free , with tag free.