These Sleeping Beauty mutants were derived by crossing F344-TgTn(T2/Bart3)2Ceb (RGD:2290163) and F344-Tg(PGK2-sb11)Ceb (RGD:2290169). This mutation consists of an insertion of a Sleeping Beauty transposable element gene trap construct into the 6th intron of the Tmco1 gene.