DNA catabolic process apoptotic DNA fragmentation Apoptosis induced DNA fragmentation DNA fragmentation in response to apoptotic signals is achieved through the activity of apoptotic nucleases. In human, these include DNA fragmentation factor (DFF) or caspase-activated DNase (CAD) and endonuclease G (Endo G) (reviewed in PMID:15723341). Caution is needed when apoptotic DNA laddering assays show presence of fragmented DNA. A positive assay may simply reflect the end point of a whole apoptotic process. Unless clear experimental evidence is available to show that a gene product is directly involved in fragmenting DNA, please do not annotate to GO:0006309 'apoptotic DNA fragmentation' and consider annotating instead to a more upstream process such as, e.g., GO:0042981 'regulation of apoptotic process', GO:0006915 'apoptotic process', GO:0097190 'apoptotic signaling pathway'. Also, note that gene products involved in compartmentalization of apoptotic nucleases and in activation or repression of their enzymatic activity should be annotated to the regulation term GO:1902510 'regulation of apoptotic DNA fragmentation' or to one of its children (see PMID:15723341). PMID:15723341 The cleavage of DNA during apoptosis, which usually occurs in two stages: cleavage into fragments of about 50 kbp followed by cleavage between nucleosomes to yield 200 bp fragments.