CCL2/MCP-1 (chemokine (C-C motif) ligand 2). Bone is one of the most common sites of prostate cancer metastasis; close to 85% of men who die of prostate cancer have bone metastasis [57] . The successful metastatic process to bone follows from the activation of osteoclasts with bone resorption, which in turns leads to the release of different growth factors from the bone matrix [58] . CCL2 has been previously reported as expressed in human bone marrow endothelial cells; the CCL2 stimulation promotes prostate cancer cell migration and proliferation [57, 59] and it has been proposed as a paracrine and autocrine factor for invasion and growth of prostate cancer [60] . As a consequence of this central role in the tumor microenvironment, CCL2 is being the object of several studies and is included in the list of potential targets for novel therapies [60, 61, 62, 63, 64, 65, 66, 67, 68, 69] .