UAS regulatory sequences (from the pVALIUM22 vector) drive expression of a shRNA that targets osk (oligonucleotide pairs for shRNA sequence are 5'-CTAGCAGTTCGACATACACTCCTGTCTAATAGTTATATTCAAGCATATTAGACAGGAGTGTATGTCGAGCG-3' and 5'-AATTCGCTCGACATACACTCCTGTCTAATATGCTTGAATATAACTATTAGACAGGAGTGTATGTCGAACTG-3').