Regulating the TRAIL of destruction: how A20 protects glioblastomas from TRAIL-mediated death.

In this issue of Cancer Discovery, Bellail and colleagues unravel how overexpression of the ubiquitin-modifying enzyme A20 results in TNF-related apoptosis-inducing ligand (TRAIL) resistance in glioblastoma. After TRAIL receptor stimulation, A20 mediates the polyubiquitination of RIP1 at the TRAIL receptor tail, resulting in the interaction of the polyubiquin chain to procaspase-8 that is recruited to the TRAIL-bound receptors. The inability of ubiquitin-bound procaspase-8 to be dimerized and activated prevents the execution of the apoptotic program.