Proteins produced by certain white blood cells [called cytotoxic T lymphocytes (CTL) or killer T cells]. The proteins allow lysis (i.e., bursting) of infected cells. Cecrophins are amphopathic (i.e., contain both a hydrophobic region and a hydrophilic region); and work by “worming” the hydrophobic portion into the cell membrane (so the hydrophobic portion of the cecrophin molecule is out of the water). This creates a transmembrane pore (i.e., a hole in the membrane) which is lined with the cecrophin’ s hydrophilic portion. Membranes function simply to separate various components. This separation is required for life to exist. When holes are introduced into cell membranes, water rushes into the targeted cell due to differences in osmotic pressure and the cell ruptures (explodes). T cecrophins are only able to lyse (i.e., burst) infected cells because only “sick” cells have a weakened cytoskeleton (located just inside the cell membrane), which cannot prevent the contents of the cell from spilling out through the pores (created by cecrophins).