On the other hand, Plumb et al. showed that 5-aza-dC-induced sensitization of human colon cancer xenografts to epirubicin, a topoisomerase II inhibitor, depends on reexpression of MLH1 gene [42], while our results indicate that 5-azanucleosides induce sensitization to topoisomerase inhibitors in MMR-deficient CRC cells (HCT116, DLD-1; Table 1). Here, MLH1 is linked to colorectal carcinoma.