HGF and cancer: The extracellular matrix density, and different extracellular molecules such as TGFβ, epidermal growth factor (EGF), hepatocyte growth factor (HGF), insulin-like growth factor (IGF), fibroblast growth factor (FGF), Notch and homologous wingless (wg), and Int-1 (Wnt) protein family are essential to force cancer cells through the invasive phenotype [24].