CXCR4 and prostate cancer: Another study found that exosomes derived from prostate cancer can increase the expression of C-X-C motif chemokine receptor 4 (CXCR4) in myeloid-derived suppressor cells (MDSCs) by activating the toll like receptor 2/nuclear factor kappa-B (TLR2/NF-kB) pathway, thereby promoting the migration of MDSCs to the TIME and enhancing the formation of TME (21).