UAS regulatory sequences drive expression of an N-terminally deleted form of Ubx (lacks the N-terminal 235 amino acids and also lacks the C-terminal region downstream of the homeodomain) in which the putative inverted nuclear export signal (NES) that overlaps the end of the W-motif has been mutated (the three core hydrophobic residues of the NES have been mutated to Ala residues). The coding sequence is tagged at the N-terminal end with C-Venus.