In our current study we employed plasma and serum at different concentrations (0–90%) as chemotactic factors for several cancer cell lines and compared their chemotactic activities to known chemoattractants, such as hepatocyte growth factor/scatter factor (HGF/SF) [6] and α-chemokine stromal-derived factor 1 (SDF-1) [7]. This evidence concerns the gene CXCL12 and cancer.