MLH1 and neoplasm: Mouse studies have shown that although Pms2−/− (van Oers et al. 2010) and Mlh3−/− (Chen et al. 2005) single knockout mutants both display microsatellite instability and tumor susceptibility, only the double knockout (Pms2−/−Mlh3−/−) mice are indistinguishable from Mlh1−/− mice for tumor susceptibility, reduced life span, microsatellite instability, and DNA-damage response (Chen et al. 2005).