UAS sequences are fused upstream of 3 copies of Tag:HA followed by a genomic fragment that encompasses exons 3 to 5 (including the variable exon 4 cluster) of Dscam1. Variable exon 4.8 has been replaced with Dscam1 variable exon 9.8. A short 3'UTR from the ewg gene is present downstream of the genomic fragment.