Telomeres are the end portions of chromosomes, among others. protecting them from inappropriate DNA repair mechanisms. Telomere length is regulated by the action of many different proteins: TRF1, TRF2, TIN2, TANK1, TANK2. TRF1 and TRF2 proteins are involved in the formation of specific structures called t-loops that protect telomeres from fusions "end to end". TANK1 and TANK2, belong to a class of proteins PARP. These proteins regulate the function of telomeres by poly-ADP-ribosylation.