RMCE on KH2 cells inserted a cassette that contains a splice acceptor, 2 polyadenylation sequence, tetracycline operator, flag-tagged mouse cDNA, and an SV40 polyadenylation signal into the 3'UTR. Leaky ectopic expression in the absence of doxycycline induction was confirmed by quantitative RT-PCR and immunohistochemistry. (J:166568)