A 4.5kb Dscam1 promoter fragment from -261 to +4309 bp (this fragment includes the 5' untranslated sequences of exon 1 and up to the exon 2 ATG codon) is fused to a Dscam1 cDNA that encodes exons 2-24 and is fused at the C-terminal end with GFP. The cDNA fragment contains the alternative exons 4.3, 6.36, 9.25 and 17.2 and exons 19 and 23 are present.