UASt regulatory sequences are fused upstream of a genomic fragment that encodes the entire ple transcription unit. A frameshift mutation (single base insertion) has been introduced near the end of exon d (an exon that is specific to the non-neural isoform). This transgene is expected to express a full-length active protein in neural tissues, but in non-neural tissues, incorporation of exon d (containing the frameshift) is expected to result in a protein that is truncated before the catalytic domain, rendering it inactive.