DFF is composed of two subunits: DFF40/CAD and DFF45/ICAD. Human DFF45 and its mouse homologue ICAD are the inhibitors of DFF40 and CAD, respectively. Cleavage of DFF45, which is mediated by caspase-3, leads to DFF40’s activation as a nuclease. Activation of DFF40/CAD can lead to DNA fragmentation, a hallmark of apoptosis. DFF40 mRNA is expressed in limited number of human tissues: pancreas, spleen, prostate, and ovary.