Our findings warrant future studies to independently validate the enrichment of PAX6 and KLF3 mutations in late-stage, MSI-hypermutated EECs, to determine expression levels of KLF3 and PAX6 proteins in endometrial tumors, and to determine the functional effects of recurrent frameshift mutations in these genes particularly in regard to phenotypic properties associated with tumor progression. Here, PAX6 is linked to neoplasm.