Full-length tissue factor (TF) is a transmembrane receptor and cofactor for factor (F)VII/FVIIa. In addition to full-length TF, an alternative spliced (as) form of TF can be generated that lacks the transmembrane domain and is released fromcells. In contrast to TF, asTF has low procoagulant activity because it lacks the transmembrane domain. Tissue factor is expressed by cells around blood vessels, such as adventitial fibroblasts, and body surfaces, such as epithelial cells, and plays a critical role in hemostasis. TF also contributes to various forms of thrombosis. Many cancers, particularly adenocarcinomas, express high levels of TF. A high level of tumor TF expression is associated with poor prognosis in many types of cancers, including breast, prostate, colorectal, and pancreatic cancer.