A sequence cassette that includes the GAL4 driver has been introduced into the attP site present in TI{TI}DskattP, restoring 551bp of sequence from upstream of the Dsk translation start site (this sequence was deleted in TI{TI}DskattP), and resulting in GAL4 being expressed under the control of endogenous Dsk regulatory sequences (the Dsk coding sequence is still absent).