Inhibition or genetic deletion of FXIII(a) results in decreased clot weight. Whole blood from F13a^+/+, F13a^+/−, and F13a^−/− mice was clotted with TF/CaCl₂ in the absence or presence of the FXIII inhibitor T101 (20 µM, final) for 2 hours. (A-B) Serum RBC content (A) and contracted whole blood clot weight (B) were recorded. Each dot is a separate mouse; lines indicate mean ± SEM.