To determine the underlying roles of the HLA-DPB2/HLA-DPB1 axis in BC, we obtained the top 100 co-expressed genes of HLA-DPB2 and HLA-DPB1 using the UALCAN database, as shown in Supplementary Table 5 and Supplementary Figure 5. This evidence concerns the gene HLA-DPB2 and breast cancer.