The Multilayered Regulation of the Oncogenic Protein YY1

The multifunctional protein Yin Yang 1 (YY1) plays critical roles in tumorigenesis. YY1 has been shown to be involved in the development, progression, resistance, and invasiveness of many types of cancers. Today, the value of YY1 as a prognostic marker and as a potential target in cancer therapy is being explored by multiple research groups around the world. Over the past 25 years, we have accumulated a wealth of information about the wide-ranging biological functions of YY1 at the molecular, cellular, and organismal levels. However, our knowledge of how YY1 is regulated and what regulates it has lagged behind. In the past few years, there has been a significant increase in the research addressing this issue. In this review, we summarize and analyze recent findings about the regulation of YY1 at multiple levels. We emphasize the necessity for deeper insights into these regulatory mechanisms if YY1 is to find its way to the clinical setting.