Interactions between the extracellular matrix (ECM) and cell surface integrins leads to podosome formation. The initiating signal is transduced through mechanosensing integrins to the cytoskeleton, upon which the actin network undergoes significant re-organization to promote formation of the podosome. It is widely believed that Arp2/3-mediated nucleation is the major means by which the podosome actin cytoskeleton is built. In addition to the known activation of Arp2/3 by Cdc42-WASP, a second weaker activator of Arp2/3 also resides in podosomes (and invadopodia), namely cortactin… Read more…