Fig. 7.

Acute insulin treatment activates S6 kinase and S6 ribosomal protein equally, regardless of preincubation conditions, in cells deprived for 2 h of FBS and low-dose insulin. Cells were treated as described in Fig. 6. The gel shown in A compares cells preincubated in 5 mM glucose with cells preincubated in 25 mM glucose + 0.6 nM insulin. After a 2-h withdrawal of FBS and low-dose insulin, cells were stimulated for 15 min with 100 nM insulin (I) or assayed in the basal state (B). Cells were lysed and immunoblotted for phosphorylated S6 kinase and for phosphorylated S6 ribosomal protein. β-Tubulin is shown as a loading control. B: quantitative analysis of cells harvested after 15 min acute insulin stimulation; n = 13 from 4 separate experiments. Glc, glucose.