EZH2 and glioblastoma: Remarkably, the histone methyltransferase EZH2, a catalytic subunit of the polycomb-repressive complex 2 (PRC2) responsible for the deposit of methyl mark on H3K27, has been reported as a fundamental and necessary contributor to the expansion of CSC compartment and the establishment of drug resistance in HGSOC, as well as PDAC and GBM [123,124,125].