Interestingly, using ccr6−/−, ccr7−/−, and cxcr4−/− fetal liver progenitors transduced with oncogenic Notch1-IC, cxcr4 rather than ccr7 was implicated in CNS infiltration by T-ALL cells, in addition to BM engraftment (24). Here, CXCR4 is linked to acute lymphoblastic leukemia.