mFRT71 is an engineered recombination target site derived from the wild-type FRT site (the target site for the FLP recombinase encoded by the Saccharomyces cerevisiae 2μ plasmid). It is composed of two 13bp inverted repeats flanking an 8bp asymmetric spacer sequence (5'-GAAGTTTCTATTCtctagaaaGTATAGAAACTTC-3') and contains mutations in both inverted repeats relative to FRT (PMID:12547191, FBrf0213120). Recombination occurs between a pair of target sites oriented in the same direction; the 13bp repeats each act as binding sites for the recombinase (PMID:3047402), while the asymmetric 8bp spacer is the site of DNA strand exchange and determines the orientation of the target site (PMID:3711092). Due to the mutations in the inverted repeats, mFRT71 is no longer a target for the native FLP recombinase (or any engineered derivative which retains the native target-site specificity), but is instead efficiently and specifically targeted by the FLPm5 recombinase variant (FBrf0213120). The recombination event results in genetic modification, the nature of which is influenced by the relative orientation (direct or inverted), location and composition of the two target sites. The types of possible modification include deletion of DNA, generation of chromosomal rearrangements, and integration of DNA into the genome (reviewed in FBrf0231034).