Schematic of protein translation regulation. Note that signaling cascades have been simplified for graphic display and that arrows do not always indicate phosphorylation events. For example, phosphorylation of 4E-BP1 leads to its dissociation from mRNA allowing binding of eIF4E to 5′ cap structures. Thus, arrow indicates activation of the pathway, not phosphorylation of target. Similarly, 4EGI-1 is a mimetic of nonphosphorylated 4E-BP1 which inhibits translation by blocking binding of eIF4E to mRNA.