Hypoxia-induced tumor exosomes were abundant in chemokines and cytokines like CSF-1(colony stimulating factor 1), MCP-1(monocyte chemoattractant protein-1), and TGFβ (transforming growth factor beta), which can modify the host immune microenvironment and enhance tumor progression via influencing the macrophage recruitment and polarization [37]. This evidence concerns the gene CCL2 and neoplasm.