CXCL9 and breast cancer: In our study, we found four differentially expressed cytokines/chemokines (CCL5, CCL19, CXCL9 and CXCL10) that regulated lymphocyte recruitment into tumor tissue and all of them were upregulated in claudin-low BCa (vs. other BCa subtypes) by the METABRIC database and in primary breast cancer patients defined as claudin-low BCa (vs. normal patients) by the TCGA-BRCA database.