FIG. 8.

Activation of PP2A by α2β1 integrin is dependent on Cdc42. (A) The effect of the transfected dominant-negative mutant forms of Cdc42 (Cdc42DN), Rac1 (Rac1DN), and RhoA (RhoADN) on the activation of PP2A in Saos-α2 cells. Phosphatase activity relative to cell lysate protein content is shown. Immunoblotting with antibodies against PP2A and Cdc42 was performed to show that Cdc42 was overexpressed in transfected cells and that it had no effect on the amount of PP2A protein in cells. (B) Serum-starved fibroblasts were detached and left untreated or treated with inhibitor BIM I (10 μM) or SB203580 (20 μM) and placed inside collagen for 1 h. Phosphatase activity relative to cell lysate protein content is shown (mean ± SEM). BIM I, four separate experiments; SB203580, two separate experiments (n = 3 for each).