Fig. 4. Fj and Ds impart positional information in the eye and wing. Fj and Ds are transmembrane proteins that are expressed in opposing gradients in the eye (A) and the wing (B). The distribution of these proteins defines the equatorial-polar axis in the eye, and the distalproximal axis in the wing. Disrupting the polarized distribution of Fj and Ds perturbs planar polarity in both the eye and wing.