Different, through homogenous, MMR protein expression patterns in distinct tumor compartments were observed in a mucinous adenocarcinoma (case 9) with loss of MLH1/PMS2 expression, MSI and MLH1 methylation in 1/7 tumor blocks that corresponded to an adenomatous tumor component (Figure 1d). The gene discussed is MLH1; the disease is mucinous adenocarcinoma.