The sharing between placental cells and cancer cells of immune suppression/immune evasion molecules such as fas ligand (Fas-L) [7], DAF [8], CD55 [9], IL-10 [10], MICA [36], HLA-G and indolamine 2,3 dioxygenase [37], as well as molecules of angiogenesis such as VEGF [11], placental growth factor [38], angiopoietin [39], FGF, EGF, and TGF-beta [40] suggests not only a functional, but also a molecular homology between placenta and cancer cells. The gene discussed is CD55; the disease is cancer.