Gene targeting strategy for B-hVEGFR1 mice. The mouse VEGFR1 gene that encode the extracellular domain were replaced by human VEGFR1 counterpart gene in B-hVEGFR1 mice.

• Strain specific analysis of VEGFR1 gene expression in wild-type mice and B-hVEGFR1 mice by RT-PCR. Mouse VEGFR1 mRNA was detectable in lung of wild-type mice (+/+). Human VEGFR1 mRNA was detectable only in homozygous B-hVEGFR1 mice (H/H) but not in wild-type mice.
• Strain specific VEGFR1 expression analysis in homozygous B-hVEGFR1 mice by flow cytometry. Pulmonary vascular endothelial cells were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hVEGFR1 mice (H/H), and analyzed by flow cytometry with anti-VEGFR1 antibody. Human VEGFR1 was exclusively detectable in homozygous B-hVEGFR1 mice but not in wild-type mice. Mouse VEGFR1 was detectable in wild type mice and homozygous B-hVEGFR1 mice, as the antibody is crossly reactive with VEGFR1 in human and mice.