A mutated form of the Amel\vg quadrant enhancer, in which the TAAT motif has been replaced with part of a Ubx-binding cassette from the D. melanogaster vg quadrant enhancer (the inserted fragment contains contains GAGA binding and TAAT motifs but not the TAAAT motif), is fused upstream of a minimal Hsp70 promoter followed by sequence encoding the EGFP fluorescent protein, tagged at the C-terminal end with a nuclear localization signal.