Figure 3.

Influence of spacer sequence on zinc-finger nuclease (ZFN) activity. HEK293T cells were transfected with plasmids encoding ZFN expression vectors, donor, and targets containing an AT-rich spacer, a GC-rich spacer, or a balanced 6-bp spacer. The bars designate the percentage of EGFP-positive cells 2 days after transfection as determined by flow cytometry. The respective linker variants and the sequence of the spacers are indicated. I-SceI was included as a negative control to indicate the level of nonstimulated gene targeting. A statistically significant increase in gene targeting relative to nonstimulated HR is indicated by * (P < 0.05) or ** (P < 0.01).