The coding sequence in exon 1 and 4 kb of sequence including exons 2-4 were replaced with a floxed Dsred-FRT-puro-pA cassette, Pax7 cDNA and an FRT flanked IRESnlacZ cassette. The splice donor site was deleted to ensure that no functional Pax3 protein could be made. Southern blot confirmed recombination. (J:90568)