the gag gene segment required in cis for transformation , between nucleotides 630 and 1149 , could substitute for the simian virus 40 enhancer in either orientation , and cells transfected with rous sarcoma virus ltr-driven plasmids containing the gag cis element had a two- to threefold increase in steady-state viral rna levels compared with plasmids lacking this region .
C0086222
enhancer
C0007634
cells