Figure 2.

Proposed feedback loop mediated by hydrogen peroxide (H₂O₂). Shown is the fragment of PDGF signaling that is mediated by PI3-kinase and PTEN and leads to PIP3 production. In addition to conventional chemotactic pathway to Rac GTPase and actin dynamics, PIP3 activates NOX assembly on the plasma membrane both directly and via Rac. NOX produces a superoxide anion radical, which is further converted to H₂O₂ as the final metabolite. H₂O₂ mediates potential feedback loops to the PDGF receptor, PTEN and cytoskeletal proteins, leading to maintained PDGF signaling and sustained migration. See the text for details.