THE chemical switch that silences genes can be flicked back to the 鈥渙n鈥�
position, contrary to what most biochemists believed.
Attaching a methyl group to DNA prevents a gene from being expressed.
Researchers thought this process was irreversible, but Moshe Szyf and his
colleagues at McGill University in Montreal have isolated an enzyme from human
lung cancer cells that removes the methyl group (Proceedings of the National
Academy of Sciences, vol 96, p 6107). The enzyme could be a target for
anticancer drugs.