MKI67 and signet ring cell carcinoma: The tumor cells of the signet ring cell carcinoma invaded into the muscularis propria without adjacent regional lymph nodes involvement, staging T2N0M0, which were positive for E-cadherin, MLH1, PMS2, MSH2, MSH6 and Ki-67 (80% of labeled cells in the hot-spots), indicating microsatellite-stable, and negative for HER2.