Fig. 4. The FLPout technique. (A) hs-FLPase catalyzes the removal of an FRT, a marker gene and a transcriptional termination signal (Term.) from the FLPout construct, allowing the constitutive promoter to drive the expression of the downstream gene sequence. (B) The photograph shows several clones generated using a FLPout-cubitus interruptus (ci) construct (Hepker et al., 1997), which can identified by the high levels of anti-Ci staining (red), in a late third instar wing imaginal disc. FRT, FLPase recombination target; hs-FLPase, heat-shock-induced FLP recombinase.