CXCR4 and leukemia: On the other hand, CXCR4 is an important player in the cross-talk between leukaemia cells and the BM microenvironment; CXCR4 expression is associated with poor prognosis in AML patients since its expression and binding to SDF1, produced by BM cells, is critical for the survival and retention of AML cells within the BM.