A genomic fragment from upstream of the Nup54 transcription start site drives expression of a chimeric transcription unit composed of Nup54 from which the first intron has been deleted (so that coding sequence from the overlapping CG43204 gene is not present) and in which the FG-repeat region has been replaced with the corresponding region from D. elegans Nup54 gene. The coding sequence is tagged at the C-terminal end with Tag:HA.