CXCL12 and cancer: To further investigate the role of the CXCL12/CXCR4 axis in the interaction between PCa cells and DRGs, sh-CXCR4 cells (to block the expression of CXCR4 in cancer cells only) and AMD3100 (to block CXCR4 in both cancer cells and neurites) were used in the co-culture system.