MRC1 and neoplasm: More precisely, PCR failed to detect MSI-H in tumor with MMR protein loss in only 2% of all MMR-D CRC (10/487), but in 12.2% of endometrial carcinomas (5/41), 11.5% of noncolorectal GI cancers (3/26), and 38.5% of “other types of tumors” (10/26).