Glutamate is removed by excitatory amino acid transporter 2 (EAAT2) present on astrocytes in association with AQP4. In AQP4 transfected cells, the glutamate transporter is internalised with antibody-AQP4 complex, implicating glutamate excitotoxicity in NMO [50,51]. This evidence concerns the gene AQP4 and neuromyelitis optica.