MLL +ALL cells expressed both CXCR4 and CXCR7, but chemotherapeutic agent‐induced apoptosis of leukaemia cells was inhibited by pretreatment with a CXCR4 inhibitor and accelerated by pretreatment with a CXCR7 inhibitor.94 This evidence concerns the gene ACKR3 and acute lymphoblastic leukemia.