Figure 1. Positive recombinant protein expression rates, relative promoter lengths, and eGFP expression levels in transfected CHO cells.

Six different vectors were each transfected into CHO cells and the number of cell expressing the eGFP gene was determined by flow cytometry after 48 h transfection. Relative expression rate was normalized for promoter size (A); Impact of MAR in combination with different promoters on eGFP gene expression levels in transfected cell pools (B). Three stably transfected pools were generated for each vector. Cells were collected and measured for the eGFP MFI with the FACS Calibur. Mean values differed significantly (*P < 0.05) between the vectors containing the CMV, RSV, or SV40 promoter and those containing the PGK, β-globin, or UBC promoter.