Gene targeting strategy for B-hFOLR4 mice. The exons 2-5 of mouse Folr4 gene that encode the full-length protein were replaced by human FOLR4 exons 1-4 in B-hFOLR4 mice.

Strain specific analysis of FOLR4 gene expression in wild-type mice and B-hFOLR4 mice by RT-PCR. Mouse Folr4 mRNA was detectable in splenocyte of wild-type mice (+/+). Human FOLR4 mRNA was detectable only in homozygous B-hFOLR4 mice(H/H) but not in wild-type mice. Strain specific FOLR4 expression analysis in homozygous B-hFOLR4 mice by western blot. Spleen and kidney tissue were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hFOLR4 mice(H/H), and analyzed by western blot with anti-FOLR4 antibody. Human FOLR4 was detectable in wild-type mice and homozygous B-hFOLR4 mice, as the antibody is crossly reactive with FOLR4 in human and mice.