CXCL9 and neoplasm: Based on the results of tumor-infiltrating immune cells calculated by the enrichment of immune cell signatures and IHC staining in the BCa tissues, we drew a preliminary conclusion that there were more tumor-infiltrating immune cells in the claudin-low BCa subtype than the other subtypes and that increased cytokines/chemokines (CCL5, CCL19, CXCL9, and CXCL10) mediating chemotaxis definitely played a predominant role in this process, which contributed to understanding the features of claudin-low BCa and developing a potential strategy for claudin-low BCa patients.