Fig. 4. Drab5-dependent basal to apical transcytosis of basement membrane. (A-C) GFP-Vkg non-expressing cells in a GFP-Vkg/+ background. The Myc clonal marker is in red; GFP-Vkg non-expressing cells are outlined (dashed lines). When polar cells only (A), or polar and outer BCs (B,C), do not express GFP-Vkg, the apical cap forms normally. (D) Wild type; (E,F) polar cells expressing Drab5^S43N (E) do not form an apical cap or (F) show a `microcap' phenotype. Frequency of caps (G) and microcaps (H) of stage 8 egg chambers in wild-type (n=625) flies, or flies expressing Drab5^S43N (n=298), Drab5^WT (n=201) or Shi^K44A (strong; n=183). Data are presented as mean±s.e.m. (see Materials and methods). Anterior is to the left. Scale bar: in A, 5 µM for A-F.