The Editors are issuing this Editorial Expression of Concern to alert readers that concerns have been raised regarding multiple duplications in Figs. 2B, 3A–D, 4B, and 5C, D in this article1.

The authors have provided documentation concerning the outcome of an investigation by The Kyung Hee University Inquire Committee that found no problems in any of the figures. The Editorial Office has been unable to confirm such findings directly with authorities at the institution in accordance with standard practice. Given the nature of the concerns raised, the Editor-in-Chief wishes to alert the readers to interpret the results presented here with caution.

Corresponding authors Insug Kang and Eui-Ju Yeo stated on behalf of all co-authors that they agree to this Expression of Concern.