Fig. 9. A model for Sog/integrin interactions in the wing. The primary proposed function of PS1ßPS integrin in modulating Sog activity in the wing. In wild-type wings, ß integrin heterodimers enhance the delivery or diffusion of an active Bmp inhibitory form of Sog into the provein domain. This non-autonomous source of Sog limits peak Bmp signaling to the center of the provein territory. In the absence of PS1ßPS, a repulsive form of Sog protein is unable to enter the provein territory, while a remaining unaffected Bmp promoting Sog activity (not shown) attracts the vein towards the mutant clone.