For nucleosomal DNA fragmentation, one of the hallmarks of apoptosis, activated caspase, an apoptosis specific cysteine protease, is required to cleave ICAD/DFF45 that releases its complexed DNase, CAD/ DFF40. The protein complex is located predominantly in the nuclei. Inconsistently, caspase alone cannot induce DNA fragmentation in the isolated nuclei without the addition of a cell extract or purified CAD/ DFF40. In this study, however, it is demonstrated that under selected conditions with 50 - 75 mM KCl or NaCl, caspase - 3 and - 7 can induce DNA fragmentation without the additional factor(s).