EIF2AK2 and metabolic disease: Three previous studies from two independent laboratories have examined the effects of the loss of PKR on metabolism in vivo24, 26, 27, and, although each of these studies has concluded that the deletion of PKR protects against the deleterious effects of a HFD, there are nonetheless substantial differences in the phenotypes reported in these previous studies, highlighting that the role of PKR in vivo in the context of metabolic disease remains to be fully clarified.