CXCL1 stimulated invasion and migration of BC cells via ERK/MMP2/9 signaling, indicating that tumor-derived CXCL1 may be connected with the high capacity of invasion observed in ER-negative BC cells, thus suggesting that CXCL1 may be a possible target in ER-negative BC therapeutics27. The gene discussed is MAPK1; the disease is neoplasm.