IGF-I–induced phosphorylation and kinase activity of Akt.
(A) Serum starved cells were untreated (−) or treated (+) with IGF-I. Total protein extracts (25 μg) from each cell line indicated were subjected to SDS-PAGE and blotted with anti-Akt, anti-p (Ser473) Akt, anti-p (Thr308) Akt, Anti-Bad, or anti-p (Ser136) Bad. (B) Cells were serum-starved for 18 hours and untreated (hatched bar) or treated (solid bar) with IGF-I. Lysates from 1 × 107 cells were immunoprecipitated with anti-Akt antibody and subjected to an in vitro kinase assay as described in “Materials and methods.” IGF-I–stimulated Akt activity is presented as fold increase, calculated by dividing the cpm of nonstimulated cells by the cpm of IGF-I–stimulated counterparts. Data represent average values of 2 independent assays.
