The cytotoxicity of MR1T cells depends on: (1) the expression of MR1 in complex with β2M on the tumor-cell surface; (2) the unknown antigen or antigens that are restricted by MR1-β2M; (3) the TCR of the MR1T cells that recognizes the MR1-β2M-ligand complex. This evidence concerns the gene MR1 and neoplasm.