We aim to discover oncoproteins that promote environmental maintenance for metastasis. In this study, we developed mice where fibroblasts can not make podoplanin (cKO mice) and transplanted cancer cells in mice, it was shown that the formation of fibroblasts around transplanted cancer was weaker in cKO than in the normal, and metastasis was significantly reduced in cKO mice. Therefore, we developed an antibody to cancer-type podoplanin that produced in the human oral carcinoma but not in the normal, and investigated tongue cancer, it was shown that metastasis and recurrence were significantly higher in cancer-type podoplanin-positive patients than in the negative, and that the five-year new metastasis-free survival rate was reduced in cancer-type podoplanin-positive patients. We think that the expression of cancer-type podoplanin is useful as a prognostic factor (July 26, 2018 press release, Okayama University).