Figure 5. Concentration-dependent effects
of imatinib on PDGF-induced versus insulin-induced
Akt/GSK-3β/p70S6kinase phosphorylation. Serum-deprived (24 h) RGC-5
cells were pretreated without (control) or with increasing
concentrations of imatinib (0.1 µM to 30 µM) for 30 min. Subsequently,
control and imatinib-treated cells were stimulated with either 30 ng/ml
PDGF or 30 nM insulin for 6 min. The cell lysates were subjected to
immunoblot analysis for Akt, GSK-3β, and p70S6 kinase phosphorylation (A-C,
and D-F) using the indicated primary antibodies (see Methods).
To normalize the changes in protein phosphorylation in the immunoblots,
we used β-actin as an internal control. Note: For data analyses, PDGF-
or insulin-induced protein kinase phosphorylation in the absence of
imatinib was normalized to 100%. The respective linear graphs shown are
the mean±SEM values from 3 experiments. The asterisk indicates a
p<0.05 compared with the respective PDGF-induced protein kinase
phosphorylation..
