Fig. 6. Serum-induced phosphorylation of eIF4GI is sensitive to inhibitors of PI3K and FRAP/mTOR. Two-dimensional tryptic peptide mapping of endogenous eIF4GI isolated from 293 cells (A) starved of serum, (B) then treated with serum for 30 min, (C) pre-treated with LY294002 for 20 min, then treated with serum for 30 min, or (D) pre-treated with rapamycin for 20 min, then treated with serum for 30 min. The map in (A) is the same as that shown in Figure 1B.