MRC1 and metastatic neoplasm: Although secondary mutations (somatic mutations) in the MMR gene existed at different loci among the intestinal, extraintestinal, primary, and metastatic tumors in the same patient, they did not cause a heterogeneous MMR-protein expression; differences were mainly noted in the microsatellite status among tumors at different sites in the intestinal and extraintestinal regions within the same Lynch patients.