The difference in effects of CXCL12M (e.g., the CXCL12-H25R mutant) and CXCL12D (disulfide-linked) on the migration of colon cancer HCT116 and HT29 and monocytic leukemia THP-1 cells was previously observed30,35. The gene discussed is CXCL12; the disease is monocytic leukemia.