Deletion extending from intron 3 of gsb-n to approximately 2.5kb upstream of the gsb transcription start site, which is replaced by an insertion and combined with point mutations resulting in two consecutive stop codons after amino acid residue 84 of gsb. Transcription of gsb is unlikely as its enhancers are located within the deleted portion, but the stop codons ensure that any RNA can only be translated into a non-functional gsb protein. This deletion was generated by Scer\FRT-mediated recombination between PBac{WH}gsb-nf06670 and an intermediate product of gsb ends-in homologous recombination (which contained an Scer\FRT site between the proximal wild-type and distal mutated copy of gsb generated by the homologous recombination event).