CRISPR-targeting inserted exons 2-26 of human DPP4 in-frame into exon 2 of the mouse gene. The insert contains four silent mutations in the coding sequence to prevent CRISPR RNP re-cleavage (see HGVS nomenclature below); it uses the human 3' UTR to terminate transcription and to prevent potential downstream splicing or RNP re-cleavage.