TP53BP1 and Fanconi anemia: (1) Cells lacking SAN1 show decreased survival in response to ICLs; (2) such cells also incur elevated DNA damage as detected by increased γH2AX levels and p53BP1 foci; (3) SAN1−/− cells display elevated levels of radial chromosomes and chromosomal aberrations in response to MMC, a diagnostic feature of Fanconi anemia; and (4) SAN1 is epistatic to the SNM1A and FAN1 nucleases, which participate in ICL repair31.