M1 protein affects fibrin clot strength. Physical strengths of the clots were measured with the addition of (A) thrombin, (B) an intrinsically activated INTEM assay, (C) extrinsically activated EXTEM assay or (D) a fibrin-based FIBTEM assay performed using ROTEM. Maximum clot formation (mm) after 1 hour is illustrated. Error bars represent standard error of the mean (∗P < .05, ∗∗P < .01, ∗∗∗P < .001, ∗∗∗∗P < .0001, 1-way ANOVA with Dunnett post hoc test, relative to each condition 0 μg/mL); n ≥ 3. EXTEM, extrinsic rotational thromboelastometry; FIBTEM, fibrinogen rotational thromboelastometry; INTEM, intrinsic rotational thromboelastometry.