Prostate cancer cellsthat have become disseminated into the circulation respond to the CXCL12-CXCR4pathway by enhanced adherence to the bone marrow endothelium and migrationacross endothelial barriers and basement membranes, ultimately adhering tocomponents of the bone marrow in response to a CXCL12 gradient [29]. The gene discussed is CXCL12; the disease is prostate cancer.