UAS regulatory sequences drive expression of the Eph coding region which is tagged at the C-terminal end with five copies of Tag:MYC. The 5' and 3' untranslated regions are not included in the construct, and nucleotides 475-486 of the cDNA sequence have been replaced with a Cavener consensus start site placed directly in front of the putative signal sequence (TTTCGAGAATGT has been changed to CAATCAAAATGG).