FIG. 7.

Overexpression of PP2A inactivates Akt. The effect of the HA-PP2A catalytic subunit or HA vector on the kinase activity of cotransfected Akt was tested. Akt was immunoprecipitated from transfected (36 h posttransfection) and serum-starved Saos-α2/α1 cells after 1.5 h of treatment inside collagen. Akt activity was determined by the ability to phosphorylate myelin basic protein (MBP). A control blot shows that the overexpression of the PP2A catalytic subunit has no effect on the amount of Akt protein in cells.