CCL2 and leukemia: ARC enhances the migration and adhesion of leukaemia cells to MSCs both in vitro and in a novel human extramedullary bone/bone marrow mouse model. ARC induces IL1β expression in AML cells and increases CCL2, CCL4, and CXCL12 expression in MSCs, both through ARC-mediated activation of NFκB. Cells from AML patients express the receptors for and migrate toward CCL2, CCL4, and CXCL12. Inhibition of IL1β suppresses AML cell migration and sensitizes the cells co-cultured with MSCs to chemotherapy.