Tumor recurrence after an extended latency period is more likely to occur in the organ where metastasis last occurred, specifically in breast and prostate cancer, supporting the above idea.186 Sun et al.187 (2005) demonstrated that SDF-1/CXCR4 is involved in the localization of tumors in the bone marrow in prostate cancer and that the activation of SDF-1/CXCR4 promotes the establishment of bone metastases. The gene discussed is CXCR4; the disease is prostate cancer.