AQP4 and neuromyelitis optica: After 24 hours of treatment with NMO-IgG1-6 (number of experiments = 39) there was a significant decrease in cultured astrocyte AQP4 expression (mean 114.9±24.3) when compared to treatment with Control-IgG (n = 12, mean 70.3±17.9, p<0.001), as measured by western blot (Wb) (Fig 1A).