In a murine study on mice bearing parental Cl66 murine mammary tumors and Cl66 cells resistant to doxorubicin (Cl66-Dox) or paclitaxel (Cl66-Pac) Wu et al. revealed the role of IL-17, CXCR2 ligands, and cancer-associated neutrophils in chemotherapy resistance and metastasis of breast cancer [260]. This evidence concerns the gene CXCR2 and breast cancer.