The Mi{MIC} element contains a mutagenic gene trap cassette that consists of a splice acceptor site, stop codons in all three reading frame, the coding sequence of EGFP and an SV40 polyadenylation signal. A y+mDint2 marker is present downstream of this sequence. The gene trap cassette and the y+mDint2 marker are flanked by inverted attP sites, which allows for the replacement of this entire sequence with DNA from a compatible donor plasmid (where the sequence to be inserted is flanked by inverted attB sites) through recombination-mediated cassette exchange (RMCE) driven by the phiC31:int integrase.
The EGFP sequence present in the Mi{MIC} element does not play a role in its mutagenic activity and is typically not expressed in Mi{MIC} insertions that are in coding introns. However, a cryptic ribosomal initiation site is present before the EGFP sequence, and thus if a Mi{MIC} element is inserted in the 5'UTR of a gene, it can act as a gene trap, resulting in EGFP expression in these cases.
A diagram of the Mi{MIC} element is available at the [GDP Transposons page](http://flypush.imgen.bcm.tmc.edu/pscreen/transposons.html)