AQP4 and neoplasm: Evaluation of AQP4/TRPV4 expression in peri-meningioma (peri-tumor) tissue compared with the main tumor of edematous meningiomas revealed significantly increased expression for AQP4 (p = 0.007) but not for TRPV4 (p > 0.05) in peri-meningioma tissue (Table 1; Fig. 2).