
Mutagenic NHEJ frequencies at on-target and off-target sites. K562 cells were transfected with plasmids encoding ZFN-224, the ZF nickase (L_KK/R_el), or an empty vector used as a negative control. PCR amplicons corresponding to the CCR5 on-target site and 13 off-target sites were subjected to high-throughput sequencing. Sequences that contained indels within the spacer region were considered to be NHEJ-mediated modifications.











