In contrast, the CIDE-N domain of ICAD is required for CAD/ICAD association.     ///    The DNA fragmentation factor (DFF) is composed of the 40-kDa CAD (DFF40) in complex with its cognate 45-kDa inhibitor (inhibitor of CAD: ICAD or DFF45).     ///    "Whereas the inactive DFF is thought to consist of the CAD/ICAD heterodimer, activated CAD has been isolated as a large (>MDa) multimer, as well as a monomer. "