Thawed samples were separated on 4% to
15% gradient gels with rabbit-polyclonal antibodies against
phospho-(Ser473)Akt (1:1000; Cell Signaling) and total-Akt, followed
by IRdye-conjugated anti-rabbit antibody (LI-COR). Bands were
normalized to the ratio of phospho-/total Akt for baseline-starved cells
on an Odyssey/LI-COR infrared system. Replicate assays on
independent cell populations were tested to obtain robust data for
mean ± SD for Western signal in mutant versus wild-type cells.