UAS regulatory sequences drive expression of four sgRNAs; two target Wnt5 (sgRNA sequences GCCAGTGGACCTGCGGGACTCGG and GCCAGCCAGTCTCACCGACGAGG) and two target Wnt6 (sgRNA sequences ATTTGGATCGAGAAGGATGTTGG and TGCCAATGACTGGATTCGGCTGG). The sgRNAs are expressed as a single polycistronic tRNA-gRNA cassette.