FLASH protein is a component of death-inducing signaling complex and might be 
involved in death receptor-mediated extrinsic apoptosis. Here we developed the 
peptide aptamer against death effecter domain recruiting domain (DRD) of FLASH 
protein and showed that the peptide bound to FLASH protein in vitro. 
Intracellular expression of the DRD-binding peptide aptamer specifically 
suppressed receptor-mediated extrinsic apoptosis but not intrinsic pathway, 
which was recapitulated by the antisense oligonucleotides for FLASH. These data 
suggest that DRD-binding peptide is not only a novel inhibitor modulating 
receptor-mediated apoptosis but also a tool for elucidating the roles of FLASH 
in apoptosis.