PROS1 and atrial fibrillation: However, after additional adjustment for medication use, 8 of the downregulated proteins were not significantly associated with AF anymore (P < .05), specifically coagulation factors Xa, IX, VII and II (F10, F9, F7, F2), tissue factor pathway inhibitor (TFPI), c4b-binding protein alpha chain (C4BPA), vitamin K-dependent protein S (PROS1), and protein Z-dependent protease inhibitor (SERPINA10).