Mice with Gt(ROSA)26Sortm66.1(CAG-tdTomato)Hze allele were crossed with Cre-deleter mice to remove loxP-flanked STOP. The Cre transgene was not passaged to the subsequent generation. After removal of the Rox flanked STOP cassettes by Dre-recombination, tdTomato fluorescence is expected in cells/tissues expressing Dre recombinase. (J:236001)