AQP1 and astrocytoma (excluding glioblastoma): As shown in Figure 4B, AQP1 expression was predominantly confined to the membrane of a proportion of tumor cells in Grade II astrocytoma, while there was wider and denser membranous and intracytoplasmic expression in Grade III and Grade IV and AQP1 expression was higher in high-grade than of low-grade group (P = 0.009, Figure 4C).