| Programmed cell death, known as apoptosis, of nonessential cells is necessary for embryogenesis, metamorphosis, tissue turnover and proper development and function of the immune system. Apoptosis causes cytoplasmic condensation, nuclear fragmentation and membrane blebbing. There are several proteins that are responsible for the balance of signals that confer cell death and/or cell survival. Among these are the proteins of the tumor necrosis factor ligand superfamily, which includes FAS (APO-1, CD95), FAS ligand (APO-1L, CD178), TRAIL and TWEAK (APO3L) and the FAS accessory protein FAF1 (FAS-associated protein factor-1). |
