As is well known, AQPs are small and represent a family of transmembrane proteins, which allow the transcellular water
transport driven by osmotic forces, and namely facilitate regulated water transport.
AQP8 is present in absorptive epithelial cells but it does not play a major role in intestinal transcellular water
Human aquaporins: regulators of transcellular water
These proteins control water relations  and act as regulators of transcellular water flow .
Owen et al., "Human aquaporins: regulators of transcellular water flow," Biochimica et Biophysica Acta, vol.
Aquaporins (AQPs), a gene family of water transmembrane channel proteins, not only ensure transcellular water transport across biological membranes  but also have been recently described as implicated in cell migration and proliferation [20,21].
In addition to its involvement in transcellular water transport, AQP1 water channel has recently been shown to be involved in cell migration and proliferation [20, 22-27, 36].
The main route of water exchange is via aquaporin(s) channels, which display an exquisite specificity for water; it is a fast-reacting system that allows water to import and export to the cells, and it also contributes to transcellular water flow (Carlsson et al., 1996).
In vivo inhibition of transcellular water channels (aquaporin-1) during acute peritoneal dialysis in rats.
In addition to transcellular water transport across the plasma membrane of epithelial and endothelial barriers, AQPs have been implicated in cell migration, proliferation, and volume regulation (Verkman, 2011).
DRIP and PRIP at the apical and basal plasma membranes, respectively, act in concert to provide a major route for transcellular water movement in hindgut epithelial cells.
transport may occur by simple diffusion through lipid bilayers or become markedly improved by the insertion of integral channel proteins (aquaporins) in the plasma membrane.