CXCL12 and neoplasm: Conversely, in pathologic conditions such as cancer, several cytokines, chemokines and factors, such as for example granulocytic-colony stimulating factor (G-CSF) (11), C-X-C-chemokine ligand (CXCL)2, CC-chemokine ligand (CCL)2, CCL5 (12) CXCL5, and CXCL12 (13) (see below Cytokine and Soluble Factors-Mediated Mechanisms) secreted by the tumor cause the block of their differentiation as well as their mobilization from the bone marrow and accumulation into the primary and secondary neoplastic lesions (10).