Epidemiological data show that heterozygosity resulted from one inactivated allele leading to haploin- sufficiency of proteins involved in DNA damage signaling and repair pathways plays an important role in tumorigenesis. Animals haploinsufficient for a certain protein have as low tumor development rates as their Epidemiological data show that heterozygosity resulted from one inactivated allele leading to haploin- sufficiency of proteins involved in DNA damage signaling and repair pathways plays an important role in tumorigenesis. Animals haploinsufficient for a certain protein have as low tumor development rates as their