CXCR2 and breast carcinoma: Furthermore, flow cytometry results show that the population of CD11b+GR1+-MDSCs in the spleen, lung, and peripheral blood of CXCR2KO mice was significantly reduced (Fig. 8E), further confirming the crucial role of CXCL1/CXCR2 axis in regulating the bio-functions of MDSCs during breast cancer progression.