In metazoans, in order to respond to environmental stress, differentiate properly, and progress normally through the cell cycle, a eukaryotic cell needs a specific and coordinated gene expression program, which involves the highly regulated transcription of thousands of genes [REF].
Despite being a powerful model organism for biology and the study of transcriptional enhancers, the tissue specific activity of less than 5% of the estimated 50,000 transcriptional enhancers in Drosophila melanogaster have been discovered [REF].