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>Addition of the RPL32 promoter has beneficial effects in the context of multiple heterologous promoters. The RPL32 promoter was placed upstream of the <i>β</i>-actin, CMV, SV40, and EF-1<i>α</i> promoter, which drove the TTG Zeo- d2EGFP expression cassette. Control constructs with the four different promoters contained either no extra DNA element, or flanking STAR 7/67/7 elements. Equal amounts of DNA were transfected to CHO-DG44, and after approximately two weeks, colonies were counted. Up to 24 stable colonies were isolated, and d2EGFP expression values were determined. The respective colony numbers are shown above the d2EGFP expression values.</table>

Biotechnology Research International

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Figure 3

Figure 3: 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 3 | 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 