The FRT cassette containing the Tre1 transcription unit has been removed from TI{GT-GAL4}Tre1FRT.Gal4 using FLP recombinase, resulting in a loss of Tre1 function. Sequence encoding a splice acceptor site and GAL4 is present downstream of the single remaining FRT site. A single loxP site is present downstream of the driver sequence (markers present in the progenitor insertion and donor plasmid have been removed using P1cre).