Relative Expression Levels Rather Than Specific Activity Plays the Major Role in Determining In Vivo AKT Isoform Substrate Specificity
Figure 4
Expression of all three AKT isoforms is sufficient for signaling down the mTORC1 pathway. (a) Protein lysates (20–25 μg) generated from HEK293 cells transfected with the pCDNA3 vector (control), or overexpressing HA-tagged myrAKT isoforms were resolved by SDS-PAGE, transferred onto membrane, and immunoblotted. Western blots are representative of experiments. Signals from serum-starved samples were quantified by densitometry and normalised to loading and expressed as fold change over myrAKT1 serum-starved samples. (b) phospho-rpS6 (Ser235/236). . (c) phospho-rpS6 (240/244). . Error bars: mean ± SEM. Statistical analysis was performed using the paired t-test (GraphPad Prism version 5.0, GraphPad Software, San Diego, Calif, USA). values >0.05 are not significant, values 0.01 to 0.05 (*), values 0.001 to 0.01 (**), and values < 0.001 (***).
