We are retracting our study because of the continued inability of the research community to replicate the key results in Figure 4, using the protocols provided in our paper. In this figure we report that the Natronobacterium gregoryi Argonaute can efficiently create double-strand breaks and edit the genome of human cells using 5′ phosphorylated single-stranded DNA as a guide. Despite the efforts of many laboratories (Protein Cell 7, 913–915, 2016; Nat. Biotechnol. 35, 17–18, 2017; Cell Res. 26, 1349–1352, 2016; PLOS One 12, e0177444, 2017), an independent replication of these results has not been reported. We are therefore retracting our initial report at this time to maintain the integrity of the scientific record. We nevertheless continue to investigate the reasons for this lack of reproducibility with the aim of providing an optimized protocol.