Figure 4.

lin acts cell-autonomously. (A) lin En–GAL4; UAS–LacZ. Activity stain reveals the En domain in lin mutants (enclosed by broken lines), which includes ectopic and normal 1° cell types and two to three rows of smooth cuticle in between. (B) Expression of UAS–Lin with En–GAL4 in lin mutants transforms all cells in the En domain into 4° cells. (C) Wild type. Two to three rows differentiate as 3° cells (arrowheads). (D) Expression of UAS–Lin with Wg–GAL4 in lin mutants restores 4° fate to five to six cells rows where Wg is expressed, but not more anteriorly. (Arrowheads) Five rows that still differentiate as 3° cells. Note that the ectopic 1° cell type is restored to smooth cuticle. Bar, 10 μm in all panels.