The RMCE cassette present in TI{TI}Dscam1KO.RMCE has been replaced by sequence encoding Dscam1 exons 3-5 in which sequence encoding the Tag:M(mCd8a) transmembrane domain, a T2A self-cleaving peptide and the GAL4 driver followed by a stop codon and the SV40 polyA site has been fused to the C-terminal end of exon 5. The presence of the T2A peptide allows the GAL4 driver to be translated separately from the non-functional Tag:M(mCd8a)-tagged Dscam1 exon 1-5 peptide fragment.