Effect of fibrinogen and PAR4 deficiency on pulmonary metastasis in immunocompetent mice. Mice deficient in PAR4 (Par4^-/-, A) or fibrinogen (Fib-/^-, C) and littermate controls in a C57BL/6 strain background were injected with B16-F10-luc cells via tail vein and pulmonary metastasis was determined as in Figure 2. (B) Par4^-/- mice were injected subcutaneously with 20 mg/kg recombinant hirudin in saline or with saline alone 15 minutes prior to tumor cell injection. Horizontal lines indicate medians. P values were determined using Kruskal-Wallis test with Dunn multiple comparison (A,C) or Mann-Whitney test (B). ko indicates knock out; het, heterozygous, wt, wild type; and ns, not significant.