Heterozygous gain-of-function mutations in EZH2 are found in follicular lymphoma and diffuse large cell B-cell lymphoma (Morin et al. 2010), in which the mutant enzyme is proposed to cooperate with its wild-type counterpart to increase the levels of H3K27me3 (Sneeringer et al. 2010). This evidence concerns the gene EZH2 and diffuse large B-cell lymphoma.