ci is separated from an Act5C promoter by Hsp70BbpolyA flanked by two FRT sites. The ci coding region is made up of a 400bp DraI/EcoRI cDNA fragment which includes the 5' ci coding sequences and eliminates a large intron, a 1.5kb EcoRI genomic fragment containing sequences from the middle of the coding region and a 6kb EcoRI genomic fragment containing 3' coding sequences.