Abstract: Pygopus (Pygo) is a new discovered component of Wnt signaling, which is located in the downstream of its core protein βcatenin and can mediate βcatenin into nucleus and activate target gene transcription. Pygo plays an important role in mammalian embryonic development and tumor formation. Recent studies show that  Pygo regulates stem cells, tumor cells and tumor stem cells by epigenetic mechanisms such as histone interpretations and modifications. Further insights into Pygo's functions and mechanisms will extend our knowledge of the Pygorelated tumors.