CCL2 and acute lymphoblastic leukemia: We previously reported that the leukemic bone marrow (BM) microenvironment has increased levels of chemokine (C-C motif) ligand 2 (CCL2) and interleukin-8 (IL-8), and that these chemokines have a positive impact on BM mesenchymal stem cells, but no direct effect on ALL cells [1].