The P{Mae-UAS.E^S} element contains UAS regulatory sequences (with no promoter sequence) at its 3' end, oriented outwards. A set of GAGA binding sites are inserted upstream of the UAS sequences to prevent position effects. A w^+mC marker is present at the 5' end of the element, and gypsy insulator sequences have been inserted between the marker and the UAS sequences to prevent the UAS sequences acting on the promoter of the marker. Of 102 insertions, none exhibited a mutant phenotype, implying that UAS activating elements without adjacent promoter sequences fail to elicit expression from proximate genes when inserted in the genome.