RMCE on KH2 cells inserted a construct, which contains (5' to 3') a splice acceptor, 2 polyadenylation sequence, tetracycline operator, a flag-tagged human LIN28B cDNA, and an SV40 polyadenylation signal, into the 3'UTR. No expression of the inserted gene is detected in the absence of doxycycline treatment. (J:177113)