Fig. 6.

Effects of overexpressing sple on polarity of cells in which either the Stan/Fz system (stan^–) or the Ds/Ft system is broken (ft^– d^–). Overexpression of sple in stan^– and the wild type reverses all or most of the P compartment to point forwards (A,B,F) but overexpression of sple in a ft^– d^– background produces a P compartment of normal polarity (H) and even the rear of the P region, which points forward in ft^– d^– (D) is now ‘rescued’ to normal polarity. Overexpression of sple in ft^– d^– flies also alters the polarity at the front of the A compartment (C,G) turning the hairs laterally, whereas overexpressing pk turns the hairs to point anteriorly (Fig. 5). Ubiquitous Sple appears to have no effect on ft^– d^– stan^– in either A or P compartments (compare E and I). Fig. S4 for expression of sple in d^– flies.