A T2A-cre-T2A-tdTomato cassette was introduced just before the stop codon in exon 3 of the mouse Fgf15 gene via homologous recombination in embryonic stem (ES) cells. An FRT-flanked PGK-neomycin cassette located 3' of the stop codon was excised through crosses with Flp recombinase-expressing mice. (J:305713)