The entire fru S exon (including its sex-specific splice sites) has been replaced by the FLP recombinase coding region. This results in FLP being expressed from the fru P1 promoter, and because the sex-specific splice sites have been removed, expression is uncoupled from the sex determination pathway.
mSG neuron projections in the subesophageal ganglion (SOG) are defective in the brains of fruFLP/fruP1.LexA adult males; the bilateral projections that usually extend toward the tritocerebrum are significantly reduced, similar to those seen in fruFLP/+ females.