PARP3 belongs to the poly-ADP-ribose polymerase (PARP) family. It plays a role in DSB (double-strand break) repair by promoting the recruitment of aprataxin-like factor (APLF) to sites of damage. It is preferentially activated by DNA breaks harbouring a 5' phosphate (5'P) [].Poly(ADP-ribosyl)ation (PARylation) is a post-translational modification of proteins []. PARP family members are PAR polymerases that initiate the reaction by converting the substrate nicotinamide adenine dinucleotide (NAD+) to ADP-ribose, and then catalyse ADP-ribose polymerisation on nuclear acceptor proteins [].