All cells in our body have the same genome. Differential gene expression determines the unique fate and function of cells. Gene expression can be regulated at various levels, from transcription to translation to post-translational modifications. Our primary focus lies in transcriptional regulation, a highly complicated process involving numerous factors. Specifically, we study how transcription activation is epigenetically regulated. Important questions include: 1) how do transcription factors and the basal transcription machinery communicate in time and space to ensure accurate and timely transcription activation? and 2) how do gene regulatory elements work together to facilitate transcription activation? The ultimate goal of our study is to unravel the molecular mechanisms by which cells turn on transcription of a new set of genes required for adapting to changes in their niches to maintain cellular homeostasis.