Fig. 7. A model for Stbm/Pk protein clustering and PCP signaling circuitry. See also text for details. (A) Model of how Stbm recruits Pk to the cell membrane (1) leading to its clustering (2). The complexes might then sequester Dsh from Fz signaling (3) and potentially target it for degradation. (B) In the R3 cell and on the distal end of a wing cell, Fz/Dsh signaling is high. Pk/Stbm is inhibited/prevented from influencing Fz/Dsh by an unknown factor. On the R4 side of the R3/R4 cell boundary and the proximal side of a wing cell, Pk/Stbm can counteract Fz/Dsh signaling (dashed arrow). Arrows: genetic (gray) and physical (black) interactions between planar polarity genes. The gene names are color coded according to their localization. See text for details.