CXCR4 helps CAR-CIK cells reach the BM and eliminate AML. Adding CXCR4, a chemokine receptor, to CAR-CIK cells increases their homing to the BM and also improves cytotoxic activity against AML. Mutant CXCR4^R334X improves BM homing but does not increase CAR-CIK cell cytotoxicity. Professional illustration by Somersault18:24.