A sequence cassette composed of an attP site, T2A-GAL4, a loxP site, the βTub56D 3'UTR, a Disc\RFP^{DsRed-Express2.3xP3} marker, a second loxP site and an FRT3 site has been inserted into the sut1 locus, at the C-terminal end of the open reading frame, resulting in the GAL4 driver being expressed as a separate protein under the control of the endogenous sut1 sequences, but with transcription being terminated by the βTub56D 3'UTR sequence.