Chemokines including CXCL5/CXCR2 are essential for MDSC recruitment in 4T1 BALB/c murine tumor models, while CCL1, CCL2, CCL5, GM-CSF, and G-CSF facilitate MDSC expansion and aggregation in the tumor milieu (71–73). This evidence concerns the gene CXCR2 and neoplasm.