CXCL1 and breast cancer: Meanwhile, it was demonstrated that CXCL1 level in the supernatants of M2-Raw264.7 macrophages was significantly higher than that in M1 phenotype or 4T1 cancer cells, and the conditional medium (CM) collected from M2-Raw264.7 did not result in the increased expression of CXCL1 in 4T1 cancer cells, indicating that CXCL1 derived from TAMs may be an independent factor that influences breast cancer metastasis (Fig. 2d).