Msn is enriched at the trailing edge of each migrating cell. (A) Msn-YFP shows a planar polarized distribution at the basal surface. (B) Follicle cell clones expressing Msn-YFP show that this protein is enriched at the back (blue arrowhead) of each migrating cell. Dots indicate filopodial protrusions at the front of the cell. (C) Basal views of control and msn mosaic epithelia stained with antibodies against β-PS. There is a slight enrichment of integrins at the leading edge of each follicle cell, which is disrupted in a clone of msn cells. All images are maximum intensity projections of the basal surface.