Fig. 4.

UCOE-CORE element provides direction-dependent, robust protection against transgene repression. Schematic illustration of the SB transposon vectors carrying the UCOE-CORE element and eGFP expression profile of individual CHO-K1 clones harboring these vectors over a seven-week period of continuous culture in the absence of puromycin selection pressure with the UCOE-CORE in either the 5′-(a) or 3′- (b) orientation. Expression of eGFP was assessed by flow cytometry. Each line in the graphs represents the expression profile of a single clone over the course of the 7 weeks of continuous culture