TFPI and COVID-19: They observed an increased expression of F3 (Tissue Factor [TF]) and decreased EPCR; however, other molecules involved in the endothelial regulation of coagulation, such as PLAT (tPA), SERPINE1 (PAI-1), TFPI (TF pathway inhibitor), THBD (thrombomodulin), and vWF (von Willebrand factor), were not significantly different in ECs treated with serum from patients with non-COVID-19 or COVID-19 pneumonia.