Fig. 6. Using UAS-FLPase and FLPout constructs to mark the descendents of Gal4-expressing cells. (A) Gal4 drives expression from the UASFLPase construct. The FLPase in turn activates the FLPout construct by deleting the sequences between the FRTs, leading to the irreversible expression of ß-gal in the descendents of cells that expressed Gal4. (B) Anti-ß-gal staining (green), showing the FLPout clones in a late third instar wing disc containing ptc^Gal4, UAS-FLPase and FLPout-lacZ. Anti-Ci staining (red) labels the anterior compartment. Note the presence of clones in the posterior compartment, which were not present in the ptc^Gal4 UAS-GFP disc (Fig. 5E). ß-gal, ß-galactosidase; Ci, Cubitus interruptus; FLPase, FLP recombinase; ptc, patched.