Fig. 4.

Constitutive activation of Akt signaling by mutant p110α. CEF that were transfected with wt or the mutant p110α were serum starved for 42 h and subsequently stimulated with PDGF for 15 min. Cells were then lysed, and the proteins were separated on a 4-20% gradient SDS/polyacrylamide gel. The transferred blot was probed with antibodies directed against total proteins or antibodies recognizing p-S473 Akt, p-T389 S6K, or p-S65 4E-BP1. Anti-4E-BP1 antibody detects both phosphorylated (^*) and nonphosphorylated forms of the protein.