CCR1 and acute myeloid leukemia: Our results show that even in a cytokine environment formed by the constitutive cytokine release and the cytokine-mediated cross talk between primary AML and bone marrow MSCs, the CCR1/CCR3-mediated effects on AML cell proliferation are divergent, and the different effects of CCR1/CCR3 inhibition on AML cell viability and proliferation can be explained by the hierarchical organization of the AML cell population (17).