The  Mi{MIC} transposon carries an  attP-flanked cassette containing the  yellow gene. This cassette can be replaced by Recombinase-Mediated Cassette Exchange catalyzed by  phiC31 integrase.

The paper  Diao et al. (2015) "Plug-and-play genetic access to Drosophila cell types using exchangeable exon cassettes" describes donor constructs with  attB-flanked cassettes encoding a variety of effector proteins including  GAL4,  GAL80 and  QF. As shown in the following figure, these proteins can be expressed in the pattern of a gene when cassettes are swapped into an intronic  Mi{MIC} insertion.

The self-cleaving T2A peptide assures that the effectors are not expressed as fusion proteins.

Diao et al. (2015) called these swappable cassettes "Trojan exons" by analogy to the  Trojan Horse. The cassettes can be introduced by injecting embryos with plasmids, but a more convenient method involves excising them from donor constructs with  cre recombinase. The P{lox(Trojan-GAL4)x3} construct illustrated below can donate  GAL4-encoding Trojan exons in all three reading frames. Donor constructs for single reading frames are also available.

Constructs generated in the above paper and from similar methods: