The list of candidate metastatic factors for cancer cells is very long and includes cell migration-promoting chemokines (e.g., stromal-derived factor 1, SDF-1), growth factors (e.g., hepatocyte growth factor/scatter factor, HGF/SF), bioactive lipids (e.g., sphingosine-1-phosphate, S1P; ceramide-1-phosphate, C1P), extracellular nucleotides (e.g., ATP, UTP), and even H+ ions [3–10]. This evidence concerns the gene HGF and cancer.