CXCL12 and Familial prostate cancer: Furthermore, CXCL8 signaling also increased the expression of CXCR4 and CXCR7 (the receptors mediating the biological activity of CXCL12) and CCR2 (a receptor activated by the ligand CCL2) in both PTEN-expressing and PTEN-deficient prostate cancer cells.