LacSwitch inducible mammalian expression system in mouse Swiss 3T3 fibroblasts

Swiss 3T3 fibroblasts were transfected with the provided plasmids of LacSwitch Inducible Mammalian Expression System (Stratagene). Stable transfectants were selected, expanded and characterised. At first, the production of CAT in these cell lines could be induced by IPTG treatment, but the inducibility was lost after a few months in culture in a reproducible manner. Further analysis revealed that the transfectants did not lose the cat gene nor the lac repressor protein. As a result, we conclude that LacSwitch Inducible Mammalian Expression System needs further modification for use in Swiss 3T3 fibroblasts.