HLA-C and cancer: Although the structure of wild-type NRAS–HLA-A1 is unknown, it likely differs from that of mutant NRASQ61K–HLA-A1 only at P7 Lys, such that the structural differences that disclosed the naturally altered NRAS peptide to the T cells of patients with cancer (15) are probably restricted to the mutation site at P7 and do not involve changes in peptide interactions with MHC.