Expression of Ctr1A cDNA (amplified from S2 cell cDNA with primers: F1 5' gcGGTACCatgagctccattaagatcgaat 3' and R1 5'gcTCTAGAcagcttttgtgagcggtcct 3'), fused in frame at the c-terminus to the epitope flag Tag:FLAG, is under the control of UASt sequences.