AQP4 and brain neoplasm: Physiologically, AQP-4 is the main channel providing water transport into the nervous system water compartments and across the BBB, while in many pathological experiments, it participates in the formation of secondary brain edema in animal models, such as brain trauma after cerebral ischemia/hemorrhage, inflammation, epilepsy, metabolic encephalopathy, and brain tumors (Papadopoulos et al., 2004; Wang et al., 2013).