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Figure 4 | BMC Biotechnology

Figure 4

From: Improved elongation factor-1 alpha-based vectors for stable high-level expression of heterologous proteins in Chinese hamster ovary cells

Figure 4

eGFP-expressing cell colonies obtained by elevated selection pressure and by targeted gene amplification. Red bars: mean eGFP levels for sets of cell colonies analysed. Concentrations represent final concentrations of MTX used. A. eGFP levels for 10 colonies obtained in the absence of MTX and in the presence of 50 nM MTX, colonies were obtained by the direct plating of transiently transfected cells. B. eGFP levels for 8 colonies obtained by growth in the presence of various MTX concentrations. Polyclonal stably transfected cell population was used for plating. C. Level of intracellular eGFP in polyclonal cell populations, obtained by primary selection in presence of 50 nM MTX and subsequent amplification in presence of various concentrations of MTX. Error bars indicate the standard deviation, n = 2. D. Number of copies of genome-integrated plasmids measured by Q-PCR for populations from panel C. Amplicons are located inside the eGFP ORF and one representative value experiment from three independent measurements is shown. Error bars represents standard deviations, n = 3.

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