Abstract: Novel physiologically active substance designated as epimorphin which is capable of being expressed by a gene hybridizing with a gene probe composed of the base sequence complementary to part of the base sequence of Sequence ID No. 1 in Sequence Listing, and which is produced by mesenchymal cells derived from human or mouse, and which shows morphogenetic activity of epithelial tissue, and isoforms of said epimorphin, base sequences encoding them, modified epimorphin, in which hydrophobic region at the carboxy terminal of said epimorphin polypeptide has been deleted or replaced by non-hydrophobic polypeptide, and polyclonal antibody or monoclonal antibody produced by the use of a full length or a part of said epimorphin as an antigen are provided. The substances of the present invention can be used for elucidation of the mechanism of diseases caused by abnormal epithelium formation, diagnosis of said diseases, or development of therapeutic methods therefor.