Intronic anterobithorax (abx) regulatory region sequence has been re-inserted into the Ubx locus by replacing the RMCE cassette in TI{TI}Ubx4kb-abx.RMCE, resulting in a locus in which the 'abxFAIRE' region (identified by FAIRE-seq as a broad region of open chromatin in the abx region) is deleted (a minimal cloning site sequence is inserted in place of the deleted region).