AQP4 and brain edema: Therefore, specific blockers of AQP4 are needed as supplementary tools for the knock-out strategy in order to determine a possible role for AQP4 in humans both in physiology and in cerebral edema, where the expression of AQP4 increases [6,24], and edema size and formation is reduced when knocking-out [7] or inhibiting AQP4 [25,26,27].