FXII-induced cell proliferation and aortic sprouting. (A-B) FXII-induced cell proliferation. HUVECs were prepared for cell proliferation assays as described in supplemental Methods. (A) The lane labeled “Cells” represents the proliferation of untreated HUVECs alone. HUVECs are stimulated with 240nM FXII plus 50μM Zn²⁺ in the absence or presence of 100μM PD98059 or 300μM peptide LRG20, TKC19, HVL21, or GKE19, respectively. The figure is the means ± SDs of 4 independent experiments. The asterisk indicates P ≤ .011. (B) HUVECs are stimulated with 240nM FXII plus 50μM Zn²⁺ in the absence or presence of 100μM PD98059, 30nM Wortmannin, 50μM LY294002, 188nM 6S6 or ASC-1, respectively. The figure is the means ± SDs of 4 independent experiments. The asterisk indicates P ≤ .012. (C-D) FXII-induced cell 5-bromo-2′-deoxy-uridine incorporation. HUVECs were prepared for cell growth assays as determined by BrdU incorporation described in supplemental Methods. (C) The lane labeled “Cells” represents the “growth” of serum-starved HUVECs alone. HUVEC growth is stimulated with 240nM FXII plus 50μM Zn²⁺ in the absence or presence of 100μM PD98059 or 300μM peptides LRG20, TKC19, HVL24, or GKE19, respectively (Table 1). The figure is the means ± SDs of 4 independent experiments. The asterisk indicates a P < .05. (D) HUVEC growth is stimulated with 240nM FXII plus 50μM Zn²⁺ in the absence or presence of 100μM PD98059, 30nM Wortmannin, 50μM LY294002, 188nM 6S6 or ASC-1, respectively. The figure is the means ± SDs of 4 independent experiments. The asterisk indicates P ≤ .032. (E) The ability of agonists to stimulate sprouting in aorta from a wild-type (WT) or uPAR KO mouse. Sprouting was stimulated with 1200nM VEGF or 16nM FXII. The bar graph is the means ± SDs number of sprouts from the aorta of WT or uPAR KO mice after each stimulus. The figures are representative of 3 experiments at each of the conditions, except that FXII treatment of uPAR KO aorta is the mean of 2 identical experiments.