To identify a surface antigen peculiar to a cell to be differentiated to a pancreas endocrine cell and derived from a human or mouse adult, and to provide a method for readily and efficiently separating an endodermal stem cell by using the surface antigen. ヒト又はマウス成体由来の膵臓内分泌細胞に分化可能な細胞に特有な表面抗原を同定し、この表面抗原を用いた、内胚葉系幹細胞の簡便かつ効率的な分離法を提供すること。 - 特許庁