To assess whether valproate could induce EZH2 expression in CLL, possibly resulting in global H3K27me3, I83-E95 cells and untreated leukemic cells from patient 1, 2 and 4 were incubated with or without 1000 μM of valproate in vitro. This evidence concerns the gene EZH2 and B-cell chronic lymphocytic leukemia.