Enhancers are the key agent of transcriptional control that instructs spatiotemporal patterning of gene expression in development. Recent whole-genome studies have identified approximately 400,000 enhancers in the human genome, suggesting that a typical human gene is regulated by ~20 enhancers. Diversification of gene regulatory mechanism by enhancers is thought to be a major source of phenotypic polymorphism among population. Moreover, mutation in enhancers often causes dysregulation of transcription program, which can ultimately lead to human diseases such as cancer. While the biological significance of enhancers is becoming increasingly clear in recent years, the basic mechanism of enhancer function has been still elusive. Especially, temporal dynamics of enhancer action has been largely unknown. Using Drosophila embryos as a model, we address these fundamental questions in the central dogma. By combining a wide-range of experimental approaches including live-imaging, biochemistry and fly genetics, we aim to elucidate fundamentally new dimension of the molecular mechanism of eukaryotic transcription.