APP and cancer: Otherwise, the surface expression of HGprt enzyme was also observed in several somatic tissue cancers [15]–[21] while an important function of APP as a tumor growth factor in the pathogenesis of several somatic tissue cancers has been suggested and APP as well as APP-like protein-2 (APLP2) are deregulated in cancer cells and linked to increased tumor cell proliferation, migration, and invasion [22],[23].