PROBLEM TO BE SOLVED: To provide an inhibitor in view of the fact that, although the inhibitory action of CLEC-2 has been expected for the application of antiplatelet drugs, anti-cancer metastatic drugs, etc., useful inhibitors have not been reported so far.SOLUTION: According to the present invention, there is provided a mutant rhodocytin lacking a platelet-aggregating ability. According to the present invention, there is also provided a pharmaceutical composition comprising the mutant rhodocytin. According to the present invention, there is provided a method for inhibiting platelet aggregation by a platelet-aggregating substance, the method comprising the step of administering the pharmaceutical composition to a subject in need thereof.SELECTED DRAWING: Figure 16【課題】CLEC-2の阻害作用は、抗血小板薬及び抗癌転移薬などの適用に期待されているが、これまでに有用な阻害剤は報告されていない。【解決手段】本発明によれば、血小板凝集能が欠失した変異型ロドサイチンが提供される。本発明によれば、上記変異型ロドサイチンを含む医薬組成物が提供される。本発明によれば、血小板凝集性物質による血小板凝集を阻害するための方法であって、それを必要とする対象に、上記医薬組成物を投与するステップを含む、方法が提供される。【選択図】図１６
