Figure 3.

Hypomorphic expression of IRS-1 and IRS-2 causes defects in PI3K activation. (A) IRS-1 immunoprecipitates blotted with 4G10, an anti-PY antibody (top panel). PI3K activity was also measured from these IRS-1 immunoprecipitates (bottom panel, n = 4). (B) As in A, but with IRS-2 immunoprecipitates. (C) PI3K activity in PY-immunoprecipitates (bottom panel), and a representative phosphatidylinositol-(3, 4, 5) trisphosphate (PIP₃) level (top). Bars represent mean ± SEM (n = 4). *P < 0.05 vs. siGFP treatment; **P < 0.01 vs. siGFP.