Some CXCR4+ GCB-DLBCLs may represent lymphoma cells arising from CXCR4high centroblasts in the CXCL12-rich dark zone and CXCR4− GCB-DLBCLs may be the transformed CXCR4low centrocytes in the light zone, where B cells interact with follicular dendritic and T helper cells. The gene discussed is CXCR4; the disease is lymphoma.