FIG. 7.

Modulation of IFN-stimulated STAT activity by Shp-2. (A and B) Serum-starved cells of Shp-2^+/+, ^+/−, and ^−/− origins and Shp-2^−/− cells expressing the vector only (Vector), lower level of wild-type Shp-2 (R3) or higher level of wild-type Shp-2 (R4) were treated with 1,000 U of IFN-α/ml (A) or 100 ng of IFN-γ/ml (B) for the indicated time periods. Nuclear extracts were prepared for EMSA as described in the legend for Fig. 2. The arrows denote the specific STATs-DNA complexes. (C and D) Shp-2^−/− cells expressing the vector only (Vector) or wild-type Shp-2 (R4) were treated with 100 ng of IFN-γ/ml (C) or 1,000 U of IFN-α/ml (D) for the indicated time periods. Whole cell extracts were subjected to SDS-polyacrylamide gel electrophoresis and then to immunoblot analyses with anti-PY-Stat1 and anti-Stat1 antibodies as indicated.