Scheme of transgene constructs and copy number.

<p>A. Transgene cassette: An eGFP stop cassette was flanked by loxP sites and the T₁₂₁ gene was placed downstream. B. Keratin bacterial artificial chromosome (BAC) transgene constructs: a transgene cassette (A) was inserted upstream of the start ATG codon in exon 1 of K18 (derived from mouse chromosome (Chr.) 15) and of K19 (derived from mouse Chr 11) in BACs using recombineering. The insertion site for the loxP-eGFP-stop-loxP-T₁₂₁ cassette is indicated by a dashed “V”. Representative genes downstream of keratin genes are indicated in boxes. Solid black bars indicate exons (E). C. Transgene copy number per diploid genome was determined by qPCR.