MRE11 and Nijmegen breakage syndrome: The importance of the role of the MRN complex in genome maintenance is indicated by a marked increase in the number of spontaneously arising chromosomal breaks followed by cell death after depletion of Mre11 in DT40 cells [13], and is also indicated by the high incidence of tumorigenesis in certain hereditary diseases: ataxia-telangiectasia-like diseases (ATLD) and Nijmegen breakage syndrome (NBS), which result from hypomorphic mutations in the MRE11 and NBS1 genes, respectively [14]–[17].