CXCR4 and neoplasm: Tumor dissemination occurs due to (i) low expression of chemokine receptors and adhesion molecules [4], (ii) underexpression of membrane-embedded CS81/CD 82 tetraspanins [14] and overexpression of tumor promoter heparanase enzyme, (iii) upregulation of CXCR4 by various growth factors and hypoxic conditions in tumor microenvironment [15] and acquisition of EM phenotype regulated by CXCR4 [15, 16].