Factor Xa, with Factor Va as a cofactor, turns factor II (also called prothrombin) into factor IIa or thrombin.

活性因子Xa和作为辅因子的因子Va将因子II（凝血酶原）转变为因子IIa（凝血酶）。

Also, vitamin K deficiency can cause hemophilia since vitamin K is needed by the liver to synthesize and release factors II, VII, IX, and X.

并且维生素K缺乏症也可引起血友病，因为维生素K参与肝脏合成及释放因子II、VII、IX和X。