When exploring its association with immune infiltration, we observed that tumors expressing CXCL9 had a low purity (high presence of immune cells within the tumor tissue, as described in the material and methods section) in the whole population of breast cancers and in the basal subtype (Figure 4b, upper and lower rows, respectively), suggesting a high infiltration of immune cells in tumor tissues (Figure 4b, first column for tumor purity). This evidence concerns the gene CXCL9 and breast cancer.