Figure 10.

PDGF-PI3K–derived pathways that affect cytoskeletal organization and cell migration. Model illustrating the signaling pathways initiated by the PDGF-R that affect actin cytoskeleton and cell migration, including the previously described p110/PI3K activity–dependent Rac pathway, which promotes lamellipodial extensions and the novel p85-PI3K regulatory subunit-triggered Cdc42 pathway. Activation of the Rac pathway triggers a number of effectors, of which Por 1, inducing lamellipodium formation, and Pak, mediating inhibition of actin stress fibers in v-Rac and v-Cdc42–expressing cells, are indicated (Lim et al. 1996; Van Aelst et al. 1996). Activation of the Cdc42 pathway also triggers a number of effectors of which, N-WASP promotes filopodia formation, and contributes to mediate the decrease in actin stress fibers and adhesion complexes induced by PDGF. Induction of both pathways control PDGF-induced cell migration on collagen.