PRODUCTION AND CHARACTERIZATION OF HUMAN-293-CELL-LINES EXPRESSING THE SITE-SPECIFIC RECOMBINASE CRE

We have constructed 293 cell lines expressing the site-specific Cre re combinase from bacteriophage P1, that acts on a 34 bp target sequence called loxP. Stably transformed cells were obtained by transfection wi th a plasmid containing Cre and a selectable marker under the control of viral promoters. The resulting 293Cre cell lines could be used to i nduce expression from adenovirus vectors containing reporter genes und er the control of a Cre responsive ''molecular switch.'' High efficien cy recombination was observed for Ad viral DNA containing loxP sites, The Cre expressing cell lines described here are likely to be useful f or several purposes: For expression of toxic gene products from Cre in ducible viral vectors, to induce recombination between loxP sites in t ransfected plasmids, and to induce deletions or rearrangements of gene s defined by loxP sites in viral genomes.