Each construct consists of 20 miRNA binding sites, with mismatches at positions 9-12, placed in the 3'-untranslated region of mCherry under the control of 10 tunable Gal4 UAS binding sites. The entire cassette is cloned in an attB vector containing gypsy insulators. phiC31-mediated positional integration was used to generate a library of 282 inducible lines covering 141 high-confidence Drosophila miRNAs, at defined landing sites on the second (attP40) and third (attP2) autosomes.