CXCR4 and acute myeloid leukemia: In fact, high CXCR4 expression level has been associated with inferior prognosis of AML (Burger & Bürkle, 2007; Spoo et al., 2007) and CXCR4 antagonists such as AMD3100 have been proven to enhance chemosensitization of AML (Nervi et al., 2009).