Figure 1.

PTEN/MMAC1 impairs growth factor-induced activation of Akt. (A) 293T cells were transfected with vector or wild-type PTEN/MMAC1. Endogenous levels of phosphorylated (Top) and total (Bottom) Akt protein levels were measured by immunoblot using an antibody that specifically recognizes Ser-473 (Top) and a pan-Akt antibody (Bottom). (B) Populations of Rat-1 cells stably expressing a Neo control vector, wild-type PTEN/MMAC1 or PTEN/MMAC1 C124S were established by retroviral infection and drug selection in G418. The expression of PTEN/MMAC1 was detected using an antibody against endogenous PTEN/MMAC (Top).The basal levels of activated Erk were analyzed by using an antibody that specifically recognizes phosphorylated, activated Erk (Middle). Total Erk protein was measured by using a pan-Erk antibody (Bottom). (C) Whole-cell lysates were prepared from Rat-1 cells stably expressing neo vector, wild-type PTEN, or PTEN C124S that were starved of serum for 24 hr and after re-exposure to serum for 30 min. Phosphorylated (Top) and total (Bottom) Akt levels were measured by immunoblot as in A.