Mi{GT-GAL4} represents a transgenic construct generated in vivo by using phiC31:int-mediated recombination to replace the attP cassette of a Mi{MIC} element insertion with a gene trap cassette from the pBS-KS-attB1-2-GT-SA-GAL4-Hsp70pA plasmid. The gene trap cassette is composed of a splice acceptor site, sequence encoding a GAL4 driver and Hsp70 termination sequences.