MRC1 and colorectal carcinoma: Our results demonstrated that CIMP-high tumors were more likely to lose expression of MMR protein, especially MLH1 and PMS2. In addition, among the 24 CRC patients with MLH1 hypermethylation, 16 patients (66.7%) had loss of expression of MLH1. In the present study, all of the 26 patients (100%) with loss of expression of MLH1 had loss of expression of PMS2. The heterodimeric nature of the MMR proteins is possibly the reason to explain our findings.