CXCL12 and neoplasm: Ipilimumab antagonizes the T cell inhibitor CTLA4 and increases survival of patients with melanoma; antagonists of CXCR4-SDF1 interactions or antagonist of other chemotactic factors (CCL2, CXXL12) are showing promising results inhibiting the arrival of helping populations to primary and secondary tumor sites, thus inhibiting tumor growth and metastasis.