UAS regulates expression of Irk1 ORF (from FI16807) with a mutation in the putative fray-binding motif (Val306 in the RFXV motif is mutated to Ala), and with mutations introduced to render it resistant to knockdown by co-expression of the Irk1 RNAi P{TRiP.JF01841}. (Every third nucleotide in the twenty base pairs targeted by the RNAi was mutated in order to introduce five silent mutations).