EZH1 and B-cell chronic lymphocytic leukemia: As H3K27me3 is typically deposited at gene promoters by Polycomb Repressive Complex 2 (PRC2) via its catalytic Ezh2/Ezh1 subunit34, these results are consistent with CLL epigenetic landscape being marked by incomplete Polycomb complex-mediated gene silencing resulting in permissive chromatin states in a fraction of cells.