MR1 and neoplasm: This anti-tumor effect was abolished in MR1-/- mice, but it did not require MR1 expression on the tumor cells, pointing to an indirect role for MAIT cells, possibly through activation of other type(s) of effector cells (35) Indeed, another study showed in a lung tumor model a tumor-controlling function of activated MAIT cells; mechanistically, anti-tumor functions were dependent upon MR1 expression by tumor cells, and directly involved NK cells.