Fibrin, isolated from bovine blood, is an insoluble protein produced in response to bleeding. Fibrin is the major component of the blood clot and is used for coagulation[1].
[1]. Paulson CN, et al. The anti-parasitic agent suramin and several of its analogues are inhibitors of the DNA bindingprotein Mcm10. Open Biol. 2019 Aug 30;9(8):190117.