The activation of coagulation factor X (FX) is arguably the most important step in the formation of blood clots. When tissue is damaged by external injury, FX activation is usually initiated by the formation of a complex between FVIIa and tissue factor, which binds and activates FX after anchoring into cellular membranes rich in anionic lipids and calcium. This key step involves the formation of a tripartite complex on the membrane, which was earlier modeled by Resource researchers and published in Blood Advances. In collaboration with the Morrissey lab at the University of Michigan, the previous model is now confirmed by a new, and first, cryo-EM structure of the tripartite complex on the membrane, a study reported as a cover story in Blood.