In mammalian cells, four different eIF2alpha kinases regulated by specific signals have been identified: HRI (iron deficiency) [3], [4]; PKR (double-stranded RNA produced in cells infected by viruses) [5]; PERK (stress situations in the endoplasmic reticulum) [1]; and GCN2 (amino acid or serum deprivation and ultraviolet light irradiation) [6], [7], [8]. Here, EIF2S1 is linked to nutritional disorder.