Fig. 1

a Schematic illustration adapted from C.H. Waddington’s "epigenetic landscape": as development proceeds, a stem/progenitor falls down a likelihood hill toward terminal differentiation at the bottom. At the molecular level, cell fate specification and differentiation are controlled by select expression of genes in the genome. b The pattern of biochemical activities on the chromosome can be characterized by next-generation sequencing-based technologies. These patterns provide a comprehensive view of the epigenome