CXCR4 and neoplasm: Remarkably, the cellular communication between leukemic cells and MSC through exosomes or across nanotubes (65, 66) and the disruption of the CXCR4/CXCL12 axis (28, 59), suggesting a key role for G-CSF in this phenomena, are consistent with our previous reports about production of pro-inflammatory factors by tumor cells (30), related to G-CSF and Gfi-1 (29).