Using IFN-γ as a measure of reactivity of 7G5.TCR-T to these cancer lines, we showed definitively that 7G5.TCR-T preferentially targets cells expressing the MR1*04 allele, while responses to over 100 MR1*01- and MR1*02-expressing cells were typically much weaker or nonexistent. This evidence concerns the gene MR1 and cancer.