Since CXCL12 is a classical ligand of CXCR4 [5] and CSF-1/CSF-1R crosstalk from prostate cancer cells to recruited macrophages was previously identified, we proposed that the feedback crosstalk from macrophages to cancer cells is partly mediated by CXCL12/CXCR4. The gene discussed is CXCR4; the disease is prostate carcinoma.