CXCR4 is a transmembrane G-protein-coupled receptor, widely expressed in several tumor types, whose binding with the chemokine CXCL12 results in the activation of down-stream signal transduction pathways such as the phosphorylation of mitogen activated protein (MAP) kinases and AKT-mediated signaling, responsible for multiple features of malignancy including chemotaxis, cell survival, cell proliferation, increased intracellular calcium and transcription of genes involved in angiogenesis, inflammation and metastasis [5, 6]. The gene discussed is CXCL12; the disease is neoplasm.