Polarized epithelial cells transport ions, water, and macromolecules from one biologic compartment to another. These processes include absorption by enterocytes and renal tubular cells; secretion by hepatocytes, endocrine cells, and exocrine cells; and exchange by alveolar and capillary endothelial cells¹,². The performance of these functions depends on a surface membrane organized into structurally, biochemically, and physiologically distinct apical and basolateral domains containing different ion channels, transport proteins, enzymes, and lipids.

The establishment and maintenance of these specialized surface-membrane domains is a multistage process. Alterations at any stage of this process could lead to cell dysfunction and ultimately a . . .