Bioinformatic analysis showed that CXCL2 was positively related to CCL20 in breast cancer patients (p value = 8.4e-31, R = 0.34) (Supplementary Fig. S27), and CXCL2 was abundant and highly secreted by PMN-MDSCs in CCL20-overexpressing tumors. Here, CXCL2 is linked to breast cancer.