Cre-mediated recombination of Ppargtm1Mtz excised the sequence between the most 5' and 3' LoxP sites, removing exons 1 and 2 and the floxed neo. Exon 1 contains the initiator methionine codon for the gamma 1 isoform and exon 2 encodes the first zinc finger of the DNA-binding domain for gamma 1 and gamma 2 isoforms. PCR confirmed recombination.