Provided are a new peptide, a vector incorporating a DNA that codes said peptide, a transformant obtained by transformation with that vector, and applications of said peptide, vector and transformant. The peptide according to the present invention comprises an amino acid sequence set forth in SEQ ID NO: 1, or an amino acid sequence obtained by substituting, deleting or adding one or more amino acids to/from the amino acid sequence set forth in SEQ ID NO: 1. This peptide and the vector incorporating a DNA that codes this peptide are suitable for use in an agent for promoting the proliferation of pancreatic hormone-producing cells, or a differentiation induction promoter that induces differentiation to pancreatic hormone-producing cells.本發明係提供一種新穎之胜肽、接合有編碼該胜肽之DNA之載體、經以該載體進行形質轉換之形質轉換體以及該等之用途。與本發明有關之胜肽，係由序列編號1之胺基酸序列，或序列編號1之胺基酸序列中，具有1個或數個胺基酸被取代、缺失及/或附加之胺基酸序列構成者。該胜肽或接合有編碼該胜肽之DNA之載體，係適合使用於促進胰臟荷爾蒙產生細胞增殖之胰臟荷爾蒙產生細胞增殖促進劑，或誘導朝向胰臟荷爾蒙產生細胞分化之誘導分化促進劑。
