Model for the regulation of the CED-10/Rac1 – WAVE/SCAR – Arp2/3 pathway by axonal guidance receptors.

UNC-40 activity supports the transport of inactive CED-10/Rac1 (Rac1-GDP, grey circles) to endosomes where it becomes activated (Rac1-GTP, red circles). Activated CED-10/Rac1 is then targeted to the plasma membrane where it is recruited by SAX-3/Robo. Activated CED-10/Rac1 can then recruit and help assemble the WAVE/SCAR complex (blue ovals), which leads to robust branched actin polymerization through the Arp2/3 complex (yellow oval). VAB-1/Ephrin inhibits the targeting of activated CED-10/Rac to the membrane thereby modulating branched actin polymerization.