Transcription is a key mechanism underlying the control of gene activities and cell identity during animal development and disease. Such genomic regulatory information is encoded in the form of a DNA/protein complex termed chromatin. Expression of genes underlying cell fate choices is coordinated by the binding of pioneer or lineage-specific transcription factors to gene-proximal promoters or distal enhancers. Time course measurements of transcription profiles in different cell types and their response to stimuli suggested that actively transcribed enhancers and binding of lineage-specific transcription factors coordinate for transcription events leading to cell type transition during development (1). Thus, cellular differentiation requires changes in transcription networks that are accompanied by dynamically altering local chromatin structure and enhancer/promoter activities at specific sets of genes.