AQP4 and astrocytoma (excluding glioblastoma): The expression of AQP4 is extremely correlated with the degree of severity of the astrocytoma (Warth et al., 2005; Zhao et al., 2012), tissue edema formation in the peritumoral region (Saadoun et al., 2002), increased cell migration (Saadoun et al., 2005; Papadopoulos et al., 2008) and disorganization of the characteristic arrangement of AQP4 in orthogonal arrays of particles (OAPS) in perivascular astrocytes endfeet (Noell et al., 2012).