PROBLEM TO BE SOLVED: To provide an isolated or purified polypeptide or a peptidomimetic used for treating or preventing cancer, treating a neoplasm or psoriasis.SOLUTION: There is provided a polypeptide or peptidomimetic comprising an amino acid sequence of a portion of a Smoothened (SMO) protein, comprising a functional fragment thereof, or a functional variant of either the portion or the functional fragment, or a fatty acid derivative thereof. Methods for inhibiting proliferation of a diseased cell, treating or preventing cancer, treating a neoplasm or psoriasis, and inhibiting the expression of genes involved in the Hedgehog signaling pathway, thereby inhibiting the Hedgehog signaling pathway, are furthermore provided by the invention.【課題】癌の治療若しくは予防、新生物もしくは乾癬の治療等に用いられる単離または精製された、ポリペプチド、またはペプチド模倣体の提供。【解決手段】スムースンド（SMO）タンパク質の一部分のアミノ酸配列を含み、その機能的断片、または該部分か該機能的断片かのいずれかの機能的変異体を含むポリペプチド、もしくはペプチド模倣体、またはこれらの脂肪酸誘導体。病気の細胞の増殖の阻害、癌の治療もしくは予防、新生物もしくは乾癬の治療、およびヘッジホッグシグナル伝達経路に係わる遺伝子の発現阻害によりヘッジホッグシグナル伝達経路を阻害する。【選択図】図１
