Induction of prothrombotic vascular endothelium. The APL cell and hemostasis: APL cells express procoagulant factors (ie, tissue factor, cancer procoagulant, procoagulant microparticles), fibrinolytic proteins (ie, plasminogen activators [u-PA, t-PA] and inhibitors [PAI-1] and their receptors [u-PA, annexin II]), and nonspecific proteases (ie, elastase), which activate coagulation and fibrinolysis. In addition, these cells possess an increased capacity to adhere to the vascular endothelium, and secrete inflammatory cytokines (ie, interleukin-1β [IL-1β] and tumor necrosis factor α [TNF-α]), which downstream stimulate the expression of prothrombotic properties of endothelial cells, leukocytes, and platelets. All of these events are reflected in the peripheral blood by alterations in the levels of circulating biomarkers of hypercoagulation, hyperfibrinolysis, proteolysis, and inflammation. u-PAR, urokinase-type plasminogen activator receptor; VEGF, vascular endothelial growth factor. Professional illustration by Somersault18:24.