5T4 oncotrophoblast glycoprotein is a transmembrane protein expressed on the embryonic tissue and various malignant tumor cell surfaces. It plays a vital role in the multiple biological and pathological processes including massive cellular migration during the embryogenesis, cell invasion associated with implantation, and neoplastic metastasis in the progression of tumorigenesis. Its restricted profile of expression stratifies criteria of tumorassociated antigen and makes it a new promising candidate for immunotherapy for cancer. Hence, illustrating this molecular function is necessary for discovering the principle of the tumor diffusion and aggravation and is helpful for developing novel and effective strategies of cancer therapy.