Homozygous embryos that lack Che-1 die before implantation, whereas heterozygous mice bearing a null allele (Che-1+/−) are viable and show no developmental or tumor-prone phenotype.7 However, under normal conditions of adult tissue homeostasis, even in rapidly proliferating tissues, replication stress and DNA breakage are relatively low, DNA damage checkpoints are not activated,23, 24, 25 and the occasional DNA breaks can be recognized and repaired even in cells that carry heterozygous DDR genes. Here, AATF is linked to neoplasm.