In conclusion, new data were provided herein to support the hypothesis that exosomes secreted from prostate cancer could upregulate the expression of CXCR4 in MDSCs, putatively by increasing engagement of TLR2 and phosphorylation of NF-κB, resulting in MDSCs accumulation into tumor microenvironment (Figure 5). Here, TLR2 is linked to prostate carcinoma.