to determine to what extent the viral long terminal repeat ( ltr ) was responsible for this suppression in undifferentiated cells , i constructed plasmids in which neo was placed under the control of the promoter sequence of the dihydrofolate reductase gene or the m-mulv ltr , and compared the biological activities of the plasmids in ltk- cells and in undifferentiated teratocarcinoma cells .
C0086860
sequence
C0007634
cells