Expression of FLP recombinase has resulted in stable inversion of the inverted Rab3 exon 2 present at the endogenous Rab3 locus in Rab3^{FRT.F3.3XFLAG}. This puts the exon in the same orientation as the rest of the Rab3 transcription unit, allowing expression of Rab3 protein that is tagged at the N-terminal end with three copies of the Tag:FLAG epitope. A single FRT3 site remains upstream of exon 2, and a single FRT site remains downstream of exon 2; these two sites cannot recombine with each other, and thus no further inversions of the exon can occur, even in the presence of FLP recombinase.