CCL2 and neoplasm: As CAR-T cells expand when interacting with the target tumor cells, massive cytokines including interleukin-6 (IL-6), interferon-γ (IFN-γ), monocyte chemoattractant protein 1 (MCP-1), and granulocyte-macrophage colony-stimulating factor (GM-CSF) were released by CAR-T cells and other immune cells.