Fig. 3. The dynamic equilibrium between polysomes and stress granules is regulated by the availability of eIF2-GTP-tRNA^Met and TIA proteins. Stress-induced activation of eIF2 kinases reduces the concentration of eIF2-GTP-tRNA^Met, allowing TIA proteins to promote the assembly of stress granules. Several eukaryotic viruses [e.g. herpes simplex virus (HSV), adenovirus (adeno), vaccinia virus (VV) and influenza virus] prevent stress-induced translational arrest by inhibiting the activity of eIF2 kinases or activating eIF2 phosphatases. Green events and arrows indicate routes leading to translational activation; red events and arrows indicate events leading to translational inhibition.