CXCL1 and breast cancer: To elucidate the primary source of CXCL1 in breast cancer, an ELISA assay was additionally performed to measure CXCL1 concentrations in the supernatants of TAMs, MDA-MB-231 cells, TAMs transfected with an empty vector (TAMs Vec), TAMs overexpressing CXCL1 (CXCL1OE), TAMs with a control short hairpin RNA (TAMs shCtrl), and TAMs with CXCL1 knockdown (TAMs CXCL1KD).