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

子Xa和作辅子的子Va将子II（凝血酶原）转变子IIa（凝血酶）。

So, it starts with a protein called thrombomodulin, which is on endothelial cells that line our blood vessels, and together with thrombin, they form a complex that also includes protein C and protein S.

这一过程从血栓调节蛋，它位于血管的内皮细胞中，与凝血酶形成一个复合物，其同时也包含蛋C和S。