The Mi{Trojan-lexA:QFAD.un} entry in FlyBase is used to denote the transgenic construct present in an insertion when it is known that the inserted element corresponds to one of Mi{Trojan-lexA:QFAD.0}, Mi{Trojan-lexA:QFAD.1} or Mi{Trojan-lexA:QFAD.2}, but it is not known which of these 3 intron phase variants the inserted element corresponds to. The Mi{Trojan-lexA:QFAD.un} element is generated in vivo by using phiC31:int-mediated recombination to replace the attP cassette of a Mi{MIC} element insertion with a 'Trojan lexA:QFAD ' cassette. The Trojan lexA:QFAD cassette consists of a splice acceptor site followed by the T2A peptide, sequence encoding a lexA::QF driver and an Hsp70 transcription termination signal. Integration of the cassette into a Mi{MIC} insertion in a coding intron (with the same phase) of a native Drosophila gene of interest will result in the cassette behaving as a 'Trojan' exon: the splice acceptor site ensures that the T2A-lexA::QF open reading frame is incorporated into the mRNA of the native Drosophila gene, while the T2A sequence truncates the native gene product and promotes the separate translation of the lexA::QF open reading frame. Thus the lexA::QF driver should be expressed under the control of the regulatory sequences of the native Drosophila gene of interest in the resulting fly line.