The Fz-GFP protein accumulates at the distal and proximal edges of socket cells. Shown in panel A and B are pupal legs from arm-fz-GFP pupae that were stained with Alexa-568 phalloidin. The actin stained bristle shafts can be seen growing up through the socket cells, which remain in the plane of the epidermis. Socket cells (arrows) are larger than the neighbouring epidermal cells, are indented on the proximal side and stain more brightly for Fz-GFP. Note the asymmetric accumulation of Fz-GFP in the socket cells. Fz-GFP accumulates preferentially at the distal/proximal boundaries of both the leg epidermal and socket cells. Panel C shows a region from a pupal head. The preferential accumulation of Fz-GFP on opposite sides of the socket cells is obvious here as well. The uneven accumulation of Fz-GFP is less noticeable in the head epithelial cells than on the leg or wing, although it can still usually be detected.