The regulatory elements of the E. coli lactose operon have recently been found to function appropriately in mammalian cells. One result is an ability to tightly regulate the transcription of certain eukaryotic genes by varying the concentration of the specific allolactose analog, isoprophy beta-D thiogalactoside in the culture medium. The experiments described here ask multiple generic questions. First, can one adapt the lac repressor gene to the tight and reversible repression of expression of the SV40 neoplastic transforming region? Second, if so, is it hen feasible to reversibly modulate the transforming action of the two viral transforming products, large and small T/t antigen? Success is this endeavor could, in turn, lead to specific analyses of the quantitative aspects of the in vivo function of each and, thereby, to insights into their specific biochemical contributions to the viral transforming process.
