After this article was published, similarities were noted between this article [1] and submissions by other research groups which call into question the validity and provenance of the reported results.

In response to queries about these concerns, the first authors provided the underlying data in S1–S3 Files.

The authors commented on aspects of how data were collected and analyzed for this study, but overall their responses did not fully resolve the concerns.

The PLOS ONE Editors issue this Expression of Concern to notify readers of the unresolved concerns discussed above, and to provide the data received from the authors.