The efficacy of AMD3100 was confirmed by detecting rapid mobilization of both AML and T‐ALL cells from the BM (Figure 2e, Supplementary videos 3, 4), a known effect of CXCR4 antagonism.8, 10 Interestingly, a significant number of leukemia cells remained within the BM parenchyma. The gene discussed is CXCR4; the disease is acute lymphoblastic leukemia.