Bristle toxin involved in caterpillar defense by participating in hemorrhagic syndrome characterized by a consumptive coagulopathy (PubMed:21177860). Exhibits procoagulant activity through selective factor X proteolytic activation (PubMed:21177860). Activates factor X in a dose- and time-dependent manner but does not activate gamma-carboxyglutamic acid domainless factor X (PubMed:21177860). Its activity does not depend on calcium ions (PubMed:21177860). Also functions as a growth stimulator and an inhibitor of cellular death for endothelial cells (PubMed:16597435). In vitro, increases proliferation of human umbilical vein endothelial cells (HUVEC) and inhibits the apoptosis induced by starvation (PubMed:16597435). Also increases slightly the complement decay-accelerating factor (CD55), which protects cells from complement-mediated lysis (PubMed:16597435). On the other hand, does not alter the release or expression of von Willebrand factor (VWF), tissue factor (F3), intercellular adhesion molecule-1 (ICAM1), interleukin-8 (CXCL8), and prostacyclin (PubMed:16597435). Does not show fibrinolytic or fibrinogenolytic activities (PubMed:21177860). Increased activity in presence of phospholipids (low concentrations) and calcium ions. Inhibited by PMSF. Not affected by EDTA and E-64. Expressed in larval bristles. Larvae. The recombinant protein is recognized by an antilonomic horse hyperimmune serum. Belongs to the hemolin family. Has no homology to any known proteases.