CCM2 protein haploinsufficiency increases ROCK-mediated vascular leak. (A) Lung and brain lysates of Ccm2^+/+ and Ccm2^+/− mice evaluated for CCM2 protein content show a 50% protein reduction in Ccm2^+/−. 1, control mouse IgG IP; 2, Ccm2^+/+ lung; 3, Ccm2^+/+ brain; 4, Ccm2^+/− lung; 5, Ccm2^+/− brain lysates. (B) Densitometry shows one-half CCM2 protein expression in heterozygous mouse lung and brain compared with WT. Error bars are means ± SE (n = 3). *, P < 0.01 compared with same organ of Ccm2^+/+ mouse. (C) Ccm2^+/+ and Ccm2^+/− mice were evaluated for basal and LPS-induced cerebral vascular leak as described in Fig. 2. Ccm2^+/− mice had significantly greater basal and induced leaks, reversible by ROCK inhibition with fasudil. Error bars are means ± SE (n = 6). *, P < 0.01; **, P < 0.03 compared with vehicle-treated Ccm2^+/+. (D) Similarly, pulmonary vascular leak was increased in Ccm2^+/− mice and was also reduced by fasudil. Error bars are means ± SE (n = 6). *, P <0.01; **, P < 0.04 compared with vehicle-treated Ccm2^+/+. (E and F). Brain and lung edema in Ccm2^+/− mice were increased, reversible by fasudil treatment. Error bars are means ± SE (n = 6). *, P < 0.01; **, P < 0.02 compared with vehicle-treated Ccm2^+/+ for both panels.