EZH2, an on-off valve in signal network of tumor cells.

Enhancer Zeste 2 (EZH2) is a histone methyltransferase catalyzing histone H3K27me3 to mediate gene silence. It is implicated in governing various biological behaviors of human malignancies. In this review, we over-review EZH2 serves as an "on-off valve"--not only as a critical epigenetic repressor, but as a brand-new activator for specific downstream targets as well. Time and space it "switching on-off" depends on the context and its cellular type. Moreover, EZH2 could act as a Tumor-Defender under certain circumstances. Moreover, the "Mutual-Inhibition" relationship between EZH2 and microRNAs is elaborated. In addition, we focus on different functions of phosphorylatied EZH2 in tumor cells. Finally, EZH2 inhibitors are summarized and newly-discovered strategies of targeting-EZH2 treatment are prospected.