Caspase-activated DNase (CAD) is an endonuclease found in the extrinsic apoptotic pathway of cells. In the absence of apoptotic signals, CAD is inhibited by ICAD (Inhibitor of Caspase Activated DNase). During apoptosis, however, caspase 3 cleaves ICAD, thereby freeing CAD to cleave the DNA at random sections of linker DNA between individual nucleosomes. These sections are the only parts of the DNA that are fully exposed when the DNA is condensed to chromatin, the standard form of DNA in vivo. Cleavage by CAD results in DNA fragments with lengths that are multiples of 180 bp, an effect known as apoptotic DNA fragmentation.