Moreover, our findings suggest that PD-L1 can contribute to cancer progression by modes other than suppressing anti-tumor immunity [1,99] and promoting the pro-metastatic functions of tumor cells by cell-autonomous and PD-1-induced manners [66]; this novel pathway may be mediated by PD-L1-induced down-regulation of cell-derived sTNFR1 and sTNFR2—that inhibit the ability of TNBC cells to produce pro-metastatic chemokines such as CXCL8, CXCL1 and CCL5—and therefore are protective and anti-metastatic. This evidence concerns the gene CXCL1 and cancer.