STOM(stomatin) is a member of a highly conserved family of integral membrane proteins. This protein localizes to the cell membrane of red blood cells and other cell types, where it may regulate ion channels and transporters. Loss of localization of STOM is associated with hereditary stomatocytosis, a form of hemolytic anemia. Although the wide distribution of stomatin and its constitutive expression suggest an important role for this protein in cell biology, perhaps as a house-keeping component, its function remains undetermined. The massive presence of stomatin in membrane-protruding folds and extensions suggests a possible structural role for this protein in the formation of these structures and/or the anchorage to the actin cytoskeleton.