A αTub84B promoter is fused upstream of a "SPARC3-D-OUT-GAL80" module that contains: a full-length attP site of 60bp, the GAL80 repressor, a second attP site (60bp, full-length site), spacer sequence and an attB site. Ribozyme sequences are also present (to prevent leaky expression in the absence of phiC31:int). phiC31:int catalyzes irreversible recombination between the attB site and one of the two attP sites; if the attP site upstream of the GAL80 repressor is utilized, GAL80 is excised (allowing GAL4-driven expression of any effectors present in the animal), while if the attP site downstream of the GAL80 repressor is utilized, GAL80 is retained (preventing GAL4-driven expression). Since both attP sites in the "SPARC3-D-OUT-GAL80" module are full-length, the recombination reaction that results in loss of GAL80 is expected to occur frequently.