EZH2 and biliary tract cancer: Accumulated EZH2 inhibitors have been pre-clinically tested, including 3-deazaneplanocin A (DZNep), GSK926, GSK-343, EPZ-005687, EPZ-011989, EI1, UNC-1999 and CPI-169 etc. DZNep is frequently used in many anti-tumor studies, it binds to S-adenosyl-l-homocysteine (SAH) hydrolase inhibitor as a competitive inhibitor of EZH2 to suppress cells angiogenesis and invasion in brain and prostate cancers [133], and to decrease viability in the putative cancer stem cells of biliary tract cancer (BTC) [134,135].