['To identify a shuttle promoter that can mediate gene expression in both insect cells and mammalian cells to facilitate the development of a baculovirus vector-based mammalian cell gene delivery vehicle.', 'Recombinant baculoviruses carrying the beta-galactosidase reporter gene under the control of an early to late (ETL) promoter of the Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) or a cytomegalovirus immediate early promoter (CMV promoter) were constructed. COS1, HeLa, CHO-K1, hFob1.19, and MCF-7 mammalian cells were tested for the expression of b-galactosidase.', 'ETL promoter activity was higher in bone-derived hFob1.19 than in COS1, HeLa, CHO-K1, or MCF-7 mammalian cells. The transient plasmid transfection assay indicated that ETL promoter activity in mammalian cells was dependent on baculovirus gene expression.'] Does baculovirus ETL promoter act as a shuttle promoter between insect cells and mammalian cells?