FIG. 6.

Overexpression of IGF-IRWT, but not that of the ATP binding mutant of IGF-IR (IGF-IRKR) leads to tyrosine phosphorylation of several intracellular proteins in response to IGF-I and IL-4 stimulation. The sizes of proteins (in kilodaltons) are given in numbers. (A) 32D cells and transfectants were serum starved and either left untreated or stimulated with IGF-I or IL-4 for 10 min. Equivalent cell lysates were immunoprecipitated (IP) with anti-pTyr. Transferred proteins on Immobilon membranes were immunoblotted with the same antibody. Asterisks denote unknown proteins, whereas known proteins are indicated by their names. PKC-δ, protein kinase C-δ. (B) 32D cells and their transfectants were treated as described in the legend to panel A. Equivalent cell lysates (100 μg per lane) were subjected to SDS-PAGE, and transferred proteins were immunoblotted with anti-IGF-IR serum. The position of IGF-IR is indicated.