Next we assessed whether the mutated Cxcr4 cDNA could rescue depletion of leukemia cells in vivo caused by CRISPR-mediated disruption of endogenous Cxcr4. Expression of Cxcr4WT or Cxcr4D99G rescued depletion of leukemia cells in the bone marrow and spleen (Figures 7C and 7D). Here, CXCR4 is linked to leukemia.