Morphology of various organs of animals is constructed by epithelial tissues, and mesenchymal cells exist around the tissues. An epimorphin is a cell membrane protein that is expressed in mesenchymal cells, particularly in a high amount neighboring epithelial cells (Hirai, Y., et al., Cell, 69, pp. 471-481, 1992). It is considered that the progress of morphogenesis of the epithelial tissue requires a signal from the mesenchymal cells (Gumbiner, B. M., Cell., 69, pp. 385-387, 1992). Epimorphins have been cloned in humans, birds, and rats as well as in mice. The presences of isoforms are known which have a different sequence of a hydrophobic site (Zha, H., et al., Genomics, 37, pp. 386-389, 1996; Hirai, Y., et al., Biochem. Biophys. Res. Commun., 191, p. 1332-1337, 1993; Oka, Y., Developmental Biological Society, 1997, May).
Epimorphin is known to be deeply involved in morphogenesis by epithelial tissues in mice, i.e., differentiation into hair on the fetal talon skin, and differentiation into luminal structure in the fetal lung (Hirai, Y., et al., Cell, 69, pp. 471-481, 1992; Koshida, S., et al., Biochem. Biphys. Res. Commun., 234, pp. 522-526, 1997). Moreover, epimorphin activates mesenchymal cells and promotes secretion of cytokines, IL-6 and IL-8 (Oka, Y., et al., Exp. Cell Res., 222, pp. 189-198, 1996). Recently, it was revealed that the addition of epimorphin to milk protein-producing SCp2 cells induces cell growth to form a branched duct structure (Hirai, Y., et al., J. cell Biol., 140, pp. 159-169, 1998). Epimorphin is expected to be effective in elucidating the mechanism of onset of diseases due to abnormality of organs, developing methods for diagnosing and treating said diseases, generating hairs, lumens, bones, and teeth, generating new blood vessels, and developing new methods for treatment of injuries (Zha, H., et al., Genomics, 37, pp. 386-389, 1996; Panaretto, B. A., Reprod. Fertil. Dev., 5, pp. 345-360, 1993; Matsuki, Y., et al, Archs. Oral Biol., 40, pp. 161-164, 1995).