MET and neoplasm: Nevertheless, in several well-controlled animal experimental models, it has been demonstrated that blockade of CXCR4 [50], CXCR7 [95], or c-Met [81] receptors by employing small molecular inhibitors; downregulation of these receptors by shRNA strategies [95]; in vivo administration of blocking antibodies against SDF-1 [50,61,96] or MCP-1 [80]; or application of S1P-binding aptamers [17] significantly diminished the process of chemotherapy- or radiotherapy-related dissemination of tumor cells to various organs.