Gene targeting strategy for B-hHER2/hTROP2 mice. The exons 2-17 of mouse Erbb2 gene that encode the extracellular and transmembrane domains were replaced by human ERBB2 exons 2-17 in B-hHER2/hTROP2 mice. The exon 1 of mouse Trop2 gene that encodes the full-length protein was replaced by human TROP2 exon 1 in B-hHER2/hTROP2 mice.

Strain specific analysis of HER2 and TROP2 gene expression in wild-type (WT) mice and B-hHER2/hTROP2 mice by RT-PCR. Mouse Erbb2 and Tacstd2 mRNA were detectable only in kidney of WT mice (+/+). Human ERBB2 and TACSTD2 mRNA were detectable only in homozygous B-hHER2/hTROP2 mice (H/H;H/H), but not in WT mice (+/+).

Strain specific TROP2 expression analysis in homozygous B-hHER2/hTROP2 mice by western blot. Kidney was collected from wild-type (WT) mice (+/+) and homozygous B-hHER2/hTROP2 mice (H/H;H/H), and analyzed by western blot with anti-TROP2 antibody. TROP2 was detectable in WT mice (+/+) and homozygous B-hHER2/hTROP2 mice (H/H;H/H) due to the cross-reactivity of antibodies.

Immunohistochemical (IHC) analysis of HER2 expression in homozygous B-hHER2/hTROP2 mice. The liver was collected from WT mice and homozygous B-hHER2/hTROP2 mice and analyzed by IHC with anti-HER2 antibody. HER2 was detectable in WT mice and homozygous B-hHER2/hTROP2 mice due to the cross-reactivity of the antibody. The arrow indicates tissue cells with positive HER2 staining (brown).