FIGURE 7.

Proposed mechanism of BCAR3-mediated enhancement of c-Src activation, cell spreading, and adhesion. Step 1, cytosolically localized Cas is recruited to membrane-proximal regions by BCAR3 through an indirect or direct interaction with BCAR3. Once at the membrane (step 2), Cas interacts with and activates c-Src. c-Src activation results in the phosphorylation of Cas, which leads to the recruitment of substrate domain binding partners such as Crk (step 3). Step 4, Cas/Crk interactions activate downstream signaling pathways important for cell spreading, migration, and invasion. BCAR3-dependent and BCAR3-independent c-Src signaling can also activate other signaling pathways important for cell proliferation and survival in the presence of antiestrogens. Step 5, BCAR3 itself activates an unidentified c-Src-independent pathway important for cell spreading.