We divided these breast cancer samples into high and low MHC-I groups according to their MHC-I signature score shown in Figure 6B. The result showed that proportions of various tumor-infiltrated lymphocytes, including CD8+ T cells, CD4+ T cells, regulatory T cells, and NK cells, were much higher in the group with a high MHC-I score, while proportions of cancer epithelial cells were much lower in this group, which solidly supported the opinion that high MHC-I expression in tumors usually correlates with more TILs in TME. This evidence concerns the gene CD4 and breast cancer.