An M2rtTA/IRES, loxP flanked GFP, polyA, and an FRT-flanked neomycin cassette were introduced immediately after the ATG codon in exon 1 of the mouse Mecom gene via homologous recombination in embryonic stem (ES) cells. The resultant mice were crossed with Flp-expressing mice to remove the selection cassette. (J:292941)