Fig. 3. L regulates Ser expression. (A) In wild-type first instar eye disc, Ser was expressed in the ventral domain and at the DV boundary. (B) In L^si first instar eye disc, ventral Ser expression was lost but posterior midline Ser expression (bracket) persisted. (C) Dlg marked cell boundaries of the eye disc shown in (D-F). (D) Composite of E,F. Ventral L^rev6-3 clone in first instar eye disc showed a decreased Ser expression within the clone (white arrow). However, L^rev6-3 clone near the posterior DV boundary did not affect Ser expression (yellow arrow). There was also a dorsal anterior clone present. (E) L^rev6-3 clones were marked by the absence of lacZ (red). (F) Anti-Ser antibody detected Ser protein expression. (G) Composite of H,I. L flp-out clones (red in H) upregulated Ser expression (green in I) in both dorsal and ventral domains of the first instar eye disc. Dlg staining (blue) marks disc cells.