Fig. 8. Schematic model illustrating the role of CK1/ in the activation of Dvl by Wnt-3a and Wnt-5a. Both Wnt-3a and Wnt-5a bind Frizzled that by unknown mechanism activates CK1/, which in turn phosphorylates Dvl. The interaction of Dvl with additional pathway-specific signalling components (including co-receptors), would direct downstream signalling. In case of Wnt-3a the co-receptor might be Lrp5/6, whereas Ror2 or Knypek might be the co-receptors for Wnt-5a. This model predicts that, when both Wnt-3a and Wnt-5a are present, Frizzled and phosphorylated Dvl will compete for binding and activation of additional signalling components. The prevalent signalling direction would thus be determined by the recruitment of the additional signalling units by phosphorylated Dvl.