The TRAIL of Death.

The TNF ligand family member termed TRAIL has been shown to induce apoptosis in a wide variety of transformed cell lines. The normal functions of this cytokine in vivo remain, however, relatively unknown. The complexity of this biological system has now increased unexpectedly with the identification of four distinct receptors for TRAIL, two of which have cytoplasmic death domains. This review will describe the known biological effects of TRAIL, as well as the structure and possible functions of its recently identified receptors.