PMS2 and cancer: We analyzed the correlation between TCOF1 expression and MSI, a strong mutator phenotype with a deficient MMR system, in different types of cancers and found that TCOF1 was significantly and positively correlated with MLH1, MSH2, MSH6, and PMS2 in almost all types but negatively correlated with EPCAM in CESC, KICH, and THYM (Figure 5B).