EZH2 and acute promyelocytic leukemia: To achieve this, APL cells were incubated with (combinations of) pharmacological compounds that included the “de-repressing” agents ATRA, the histone deacetylase inhibitor valproic acid and EZH2 inhibitor DZNep, which reduces EZH2 protein levels and thereby the level of H3K27me3 at transcriptional start sites of certain genes [22].