In order to understand the effect of MCU on the tumor microenvironment and immune cells of gastric cancer patients, we first analyzed the pathways and mechanisms that MCU may affect immunity in gastric cancer patients, and the results showed that the effect of MCU expression on immunity was mainly enriched in MHC and MHC class II protein complex binding, immunoglobulin complex, antigen binding, Antigen processing and presentation, ECM−receptor interaction, Th1, Th2 and Th17 cell differentiation, Refer to Figure 3A for details. This evidence concerns the gene HLA-C and neoplasm.