Figure 1.

Adhesion to matrix proteins induces STAT5A tyrosine phosphorylation. Serum-deprived HUVECs or ECV304 cells were detached with 10 mM EDTA and plated for 15 min on dishes coated with PL, FN (A), LM (B), or β1 integrin antibodies (C) or kept in suspension (S). Cell extracts were immunoprecipitated (IP) with antibodies to STAT5A or STAT5B proteins and subjected to 8% SDS-PAGE. Proteins were electrophoretically transferred to nitrocellulose filters and immunoblotted (IB) with an anti-phosphotyrosine antibody (Py) (upper panels). The filters were stripped and reprobed with the indicated antibody (lower panels). The position of the tyrosine-phosphorylated STAT5A is indicated. Five individual experiments were performed with similar results.