KAP1 controls endogenous retroviruses in embryonic stem cells
More than forty per cent of the mammalian genome is derived from retroelements, of which about one-quarter are endogenous retroviruses (ERVs). Some are still active, notably in mice the highly polymorphic early transposon (ETn)/MusD and intracisternal A-type particles (IAP). ERVs are transcriptionally silenced during early embryogenesis by histone and DNA methylation (and reviewed in ref. 7), alth