Et(icre)21603Rdav

An enhancer trap transgenic approach was used to generate these mice. The Calb1-icre transgene was designed with a 300 bp minimal promoter from the mouse calbindin 1 locus, a codon-improved cre recombinase (icre; improved with mammalian codon usage, no putative cryptic splice sites, altered stop codon, and reduced CpG content to limit the chances of epigenetic silencing in mammals), and an SV40 late polyA signal. This transgene was injected into C57BL/6J mouse embryos. Founders were crossed to C57BL/6 animals. Animals were crossed to B6-Gt(ROSA)26Sortm1Sor mice to assess cre activity/transmission. Cre positive, lacZ negative mice were subsequently bred to C57BL/6 mice to establish the 21603 line. (J:150856)