CCL2 and central nervous system cancer: As immune cells originating from the myeloid lineage, macrophages infiltrate tumor tissue driven by chemokines such as CSF-1 (Colony-stimulating factor 1) 21, 25, MCP-1 (monocyte chemoattractant protein 1) 26, 27 and SDF-1 (Stromal cell-derived factor 1) 28, 29 secreted by glioma cells, playing roles in anti-tumor (sTAMs, M1; expressing markers like HLA-DR, iNOS, and CD11c ) and pro-tumor (pTAMs, M2; expressing markers like CD163, CD206, and ARG1) functions 15, 30-32.