CXCL14, a natural inhibitor of the CXCL12-CXCR4 axis, specifically bound to CXCR4 with high affinity and inhibited CXCL12-mediated chemotaxis and migration of human bone marrow-derived hematopoietic progenitor cells and leukemia-derived cells 173. Here, CXCR4 is linked to leukemia.