Our recent work linking EZH2 expression to normal fetal retinal development and retinoblastoma indicates that this epigenetic marker does not distinguish among fetal neuroretinal progenitor cells, retinoblastoma, and IM.4 Inasmuch as EZH2 is tightly linked to cellular proliferation,8 this epigenetic enzyme may simply be enriched in retinal cells undergoing rapid proliferation, which occurs during retinal development and tumorigenesis. This evidence concerns the gene EZH2 and retinoblastoma.