Enhancer of zeste homolog 2 (EZH2) is a subunit of the Polycomb-Repressive 
Complex 2 (PRC2), which catalyses the trimethylation of histone H3 on Lys 27 
(H3K27) and involves in genes repression. EZH2 is amplified and overexpressed in 
a variety of cancers, including prostate and breast cancer. Overexpression of 
EZH2 has been associated with the invasion and progression of malignant cancers, 
especially with the progression of prostate cancer. Here, we review the 
structure and biological function of EZH2, especially focused on its activities 
in the tumorigenesis.