The observed lymphocytic tumor infiltration pattern (of both CD4+ and CD8+ cells), the elevated expression of immune checkpoints (particularly PD-L1 and CTLA-4) and the identified FSMs in coding regions of potential MSI target genes supports these ideas; thus being indicative for an active involvement of the immune system on MLH1-/- driven carcinogenesis. Here, MLH1 is linked to neoplasm.