PRDM9 and neoplasm: The “writer” of H3K27me3, Enhancer of zest homolog 2 (EZH2), has been known to be involved in tumor progression and is the catalytic subunit of Polycomb repressive complex 2 (PRC2), which is a highly conserved histone methyltransferase that targets lysine-27 of histone H3 [96,97].