Placing the RPL32 Promoter Upstream of a Second Promoter Results in a Strongly Increased Number of Stably Transfected Mammalian Cell Lines That Display High Protein Expression Levels

<table>The beneficial effects of the RPL32 promoter on heterologous promoters are also observed in serum-free suspension cell lines. A construct in which the RPL32 promoter was placed upstream of the CMV promoter was compared to constructs with the CMV promoter, but without any DNA elements, or to a construct with STAR elements, as well a construct in which the RPL32 promoter alone drove the expression cassette. The constructs were transfected to serum-free suspension CHO-DG44-S cells. After two weeks, the percentage of green cells was determined, as shown in the numbers above d2EGFP values. Then subclones were isolated and propagated, and d2EGFP values were determined.</table>

Biotechnology Research International

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Figure 6

Figure 6: Placing the RPL32 Promoter Upstream of a Second Promoter Results in a Strongly Increased Number of Stably Transfected Mammalian Cell Lines That Display High Protein Expression Levels 

Figure 6 | Placing the RPL32 Promoter Upstream of a Second Promoter Results in a Strongly Increased Number of Stably Transfected Mammalian Cell Lines That Display High Protein Expression Levels 