Pulmonary vascular integrity in the S100a10^−/− mouse. (A) Genomic organization of wild type and targeted alleles after homologous recombination. SacI fragments for wild-type and mutant alleles are indicated by double-headed arrows. Numerals 1–3 refer to exons. The vertical arrow indicates the binding site for the Southern blot probe. (B and C) PCR and Southern blot analysis of tail tip DNA from founder mice (S100a10^+/− or S100a10^+/+). In C, fragments correspond to wild-type (9.4 kb) and mutant (9.7 kb) alleles. (D) Immunoblot of pan-cadherin (loading control), ANXA2, and S100A10 in lung tissue extracts from wild-type, S100a10^−/−, and Anxa2^−/−, mice. (E) EB extracted from whole lung tissue from S100a10^+/+ and S100a10^−/− mice treated with FiO₂ 0.21 or 0.10 (48 h, n = 5 animals per group, ANOVA). (F) Pulse oximetry estimation of hemoglobin saturation for S100a10^+/+ and S100a10^−/− mice treated as in E (n = 8–9 per group, ANOVA). (G) ELISA of albumin in BAL fluid from wild-type, S100a10^−/−, and Anxa2^−/− mice maintained at FiO₂ 0.21 or 0.10 for 48 h (n = 4–7 mice per group, ANOVA). All data are representative of three to six separate experiments. Wild-type, S100a10^−/−, and Anxa2^−/− mice are indicated by black, gray, and white bars, respectively. Data are expressed as mean ± SEM. **, P < 0.01; ***, P < 0.001.