AQP4 and glioma: The study by Simone et al. (2019) found that M1-AQP4 contributes to the invasiveness of glioma cells, while aggregation in OAPs by M23-AQP4 is deleterious and promotes apoptosis, interestingly indicating that the increased invasiveness was because of the increased activity of matrix metalloproteinase-9 (MMP9), which is associated with glioma cell proliferation and patient survival rate (Xue et al., 2017).