Gene targeting strategy for B-hFGF21 mice. The exons 1-3 of mouse FGF21 gene that encode the full-length protein were replaced by human FGF21 exons 2-4 in B-hFGF21 mice.

Strain specific FGF21 expression analysis in wild type (WT) C57BL/6 mice and B-hFGF21 mice by ELISA. Serum was collected from WT mice (+/+) and homozygous B-hFGF21 mice (H/H) and analyzed by ELISA with FGF21 ELISA kit. Mouse FGF21 was detectable in WT mice (+/+). Human FGF21 was detectable in homozygous B-hFGF21 mice (H/H). Values are expressed as mean ± SEM.