The phosphorylation of 4E-BP1 correlates with activation of Akt and is sensitive to wortmannin. A. Akt is phosphorylated after IR. The cells were incubated for 1 h after IR with or without 30 μM wortmannin and then processed for western blot for either total Akt (lower panel) or Akt phosphorylated at Thr 473 (upper panel). B. wortmannin reduces the phosphorylation of 4E-BP1 which is induced by IR. The cells were incubated as in A, and analyzed by western blot for total 4E-BP1. The position of the 3 forms of 4E-BP1, from unphosphorylated (α) to hyperphosphorylated (γ) are indicated. A western blot for eIF4E is also shown.