Furthermore, although it is well established that cells deficient in BRCA1, BRCA2, Fanconi anemia, or other HR-related genes are hypersensitive to DSB inducers (Murai et al., 2012), as for instance, synthetic lethality in BRCA1- or BRCA2-deficient tumors through PARP inhibition is already approved as therapy in breast and ovarian cancer (Metzger-Filho et al., 2012), data demonstrating sensitivity of MMR-deficient cells to DSB inducers have not been conclusive (Takahashi et al., 2011; Vilar et al., 2011; Park et al., 2013). This evidence concerns the gene MRC1 and ovarian cancer.