Juvenile hormones (JH) regulate a wide variety of developmental and physiological processes in insects. As a first step in understanding the molecular mechanisms of JH action, we are identifying juvenile hormone response elements (JHRE) and proteins that bind to these JHREs. The JH-induced genes in the fruit fly, Drosophila melanogaster L57 cells and in the honey bee Apis mellifera were identified by microarray analyses. Comparative analysis of microarray data identified 16 genes that were induced by JH in both fly cells and bees. Analysis of promoter regions of these 16 D. melanogaster genes identified one common element, D. melanogaster JH response element 1 (DmJHRE1). Nuclear proteins isolated from L57 cells bound to DmJHRE1. Reporter constructs containing the â-galactosidase or the luciferase gene regulated by DmJHRE1 were constructed. In D. melanogaster cells, the DmJHRE1-regulated reporter gene was induced by JHIII, but the JHIII induction was not suppressed by 20-hydroxyecdysone (20-E). Using the DmJHRE1 DNA-affinity column chromatography and LC-MS/MS, two proteins that bind to DmJHRE1 were identified. RNAi experiments showed that DsRNA prepared based on the sequences of these two DmJHRE1 binding proteins inhibited JH III induction of reporter gene regulated by DmJHRE1. Further studies on functional characterization of the two DmJHRE1 binding proteins are in progress.