We then tested inhibitors of cytokines released by MSCs and being able to modulate AML cell proliferation (31–35), including (i) antibodies against VEGF, HGF, bFGF, and IL-6; (ii) the CCR1 antagonists BX471 (17) and BX513 (18); (iii) the combined CCR1 and CCR3 antagonist UCB35625 and its stereoisomer J113863 (19, 20); and (iv) the CXCR4 antagonist AMD3100 (13). Here, CXCR4 is linked to acute myeloid leukemia.