MLH1 and gastric cancer: Hypermethylation of the promoter of the hMLH1 gene reportedly plays an important role in mismatch repair during DNA replication and is significantly associated with microsatellite instability.66 A total of 71.4% of MSI-positive GC tumors showed hypermethylation, whereas only 29.8% of MSI-negative tumors were hypermethylated at the hMLH1 promoter region.