EZH2 and acute lymphoblastic leukemia: The fact that histone methyl-transferase EZH2 has been demonstrated to repress p57KIP2 expression through histone H3 lysine 27 trimethylation (H3K27me3) [14], and that p57KIP2 is methylated in nearly 50 % of newly diagnosed ALL patients [15], prompted us to analyze the status of cellular genes involved in chromatin silencing.