The transgene construct included 530 bp of 5'-flanking quail TnIFast (TNNI2) gene sequence (promter), exon 1, intron 1 containing the IRE-enhancer, and the untranslated exon 2 sequence up to the ATG initiation codon. The improved cre (icre) coding sequence replaced exon 2 sequences downstream of the ATG and was linked to the SV40 splicing and polyadenylation signals. (J:155917)