UAS sequences drive expression of full length ey in which the sequence of ey C-terminal to the homeodomain has been replaced by the equivalent region of toy.
eye | ectopic, with Scer\GAL4dpp.blk1
leg, with Scer\GAL4dpp.blk1
ey::toytoyPD-EYBB.Scer\UAS; Scer\GAL4dpp.blk1 adults often have ectopic eyes on their legs, but never on their antennae.