FIG. 9.

Effect of IRS protein overexpression on IGF-1-induced immediate-early gene expression. (A) After overnight serum starvation, cells were stimulated with 10 nM IGF-1 for 30 min at 37°C. RNA samples extracted from serum-starved or IGF-1-stimulated cells were separated on formaldehyde-containing agarose gels and transferred to nylon membranes. Equal loading and integrity of the RNA were confirmed by ethidium bromide staining of agarose gels (upper panel). Blots were hybridized with a specific probe for the egr-1 gene as described in the text and visualized by autoradiography (lower panel). (B and C) The blots were quantified on a Molecular Dynamics PhosphorImager. Results are expressed as percentages of IGF-1-induced WT cells (B) and the increases from basal values by IGF-1-induction from the basal condition (C). Data represent the mean and SEM of three independent experiments.