FIG. 3.

PSMA increases β₁ integrin signaling in endothelial cells. (A) PSMA-dependent in vitro motility of HUVECs is specifically mediated through laminin (n = 3; P = 0.005) but not other matrix proteins. (B) PSMA antagonists inhibit basal adhesion of HUVECs to laminin equally as well as neutralizing β₁ antibodies (Neut. Ab) do, but have no significant effect on binding to fibrinogen, fibronectin, or collagen. (C) Inhibition of PSMA interferes with activated β₁ integrin (activated with HUTS-21 antibody) binding to laminin but not other substrates (n = 3; P = 0.002). (D) PSMA inhibition in the presence of the consitutively activating β₁ antibody TS2/16 does not alter adhesion to laminin or fibronectin. (E) HUVECs transfected with siRNA targeted against PSMA show reduced basal (n = 3; P = 0.028) and β₁-mediated (n = 3; P = 0.001) adhesion compared to that of cells transfected with control siRNA; (F) HUVECs treated with PMPA or anti-PSMA antibody have decreased levels of phosphorylated FAK. *, 0.05 < P > 0.01; **, 0.01 < P > 0.001. Error bars indicate standard deviations.