Fig. 10. Model of NC polarization by Wnt/PCP and Syn4. Non-canonical Wnt signaling (Wnt/Dsh/PCP) activates RhoA, which in turn inhibits Rac activity, whereas Syn4 (activated by Fibronectin, Fn) inhibits Rac activity directly. The concerted activation of these parallel pathways leads to the inhibition of Rac (green) at the back of the cell, with the consequent formation of cell protrusions at the front of the cell and directional migration (thick arrow). There is also evidence of an interaction between Syn4 and Dsh (broken arrow).