Before revision:  Here, we show that the extraordinary strain-stiffening response of fibrin clots reflects the hierarchical architecture of the fibrin fibers , which are bundles of wormlike protofibrils .
After revision:  Here, we show that the extraordinary strain-stiffening response of fibrin networks is a direct reflection of the hierarchical architecture of the fibrin fibers , which are bundles of wormlike protofibrils .