1IBX167713368ENSG00000169598ENSMUSG00000029027O76075O54788NM_001320136NM_007859NP_001269598NP_001307061NP_001307065NP_004393NP_031885Caspase-activated DNase (CAD) or DNA fragmentation factor subunit beta is a protein that in humans is encoded by the DFFB gene.

The apoptotic process is accompanied by shrinkage and fragmentation of the cells and nuclei and degradation of the chromosomal DNA into nucleosomal units.

[11] It remains inactive in growing cells while it is associated with its inhibitor (ICAD, DNA fragmentation factor 45 kDa subunit, DFFA or DFF45) resulting into a complex ICAD-CAD.

What is more, combining C3’s amino acids leads to 5 α helices, 4 β lamina and a loop at the catalytic C-terminal which interact with each other.

[8][14][18] DFFA is encoded by an alternatively encrypted mRNAs originating two distinct forms: short (ICAD-S) and long (ICAD-L), which act like a specific chaperone ensuring the correct CAD's folding[10][11][17] Besides, it contains two aspartic acid residues (Asp117 and Asp224) where CAD is identified and, consequently, it stays bounded until Caspase-3 splits this union.

Besides, Caspase 3 induces DNA breaks in the promoter of the factor p21 and this strand breakup is related to p21 gene expression.

The protein caspase DNase is an endonuclease involved in the cell apoptotic process that facilitates the DNA breakup.

This biological response is characterized by the chromosomal DNA’s degradation in tiny fragments within the nucleus of the cell.

[28] After many investigations and research, it was possible to ensure that Caspase-activated DNase is the main responsible of this destruction due to a long list of stimuli.

This was the key evidence to prove that the CAD form is implicated in this part of the process because without its contribution the fragmentation did not take place.

[29] Later, it was found that the way how this protein induces the DNA breakup is explained by its forms CAD and ICAD, which facilitate both the entry and exit in the nucleus of the cell.