Upon SLIT-mediated ROBO stimulation, SOS1 or SOS2 is recruited into the multiprotein complex consisting of SLIT2, ROBO1 and the SH3-SH2 protein NCK1 or NCK2 (orthologues of Drosophila Dock). NCK bridges the physical association between ROBO and SOS. This interaction was demonstrated in both Drosophila and human cells (Hu et al. 1995, Fritz et al. 2000, Yang and Bashaw 2006).