Expression of Concern. Protein Kinase C (PKC)-α Activation Inhibits PKC-ζ and Mediates the Action of PED/PEA-15 on Glucose Transport in the L6 Skeletal Muscle Cells. Diabetes 2001;50:1244–1252. DOI: 10.2337/diabetes.50.6.1244. PMID: 11375323

On the basis of the recommendation of the American Diabetes Association’s Panel on Ethical Scientific Programs (ESP), the American Diabetes Association, the publisher of Diabetes, is issuing this expression of concern to alert readers to questions about the reliability of the data in the above-cited article.

After readers of the journal contacted Diabetes about potentially duplicated images in the article, the ESP reviewed the following issues:

• In Fig. 2, lanes 2 and 4 appear to be duplicates.

• Figure 6 appears to contain the following potentially duplicated images:

  • ∘ In the “Total Glut 4” strip, lanes 2, 3, 6, and 7 appear to be duplicates. Likewise, lanes 4 and 8 appear to be duplicates.

  • ∘ In the “P.M. Glut 1” strip, lanes 5 and 7 appear to be duplicates. Lane 3 appears to be a duplicate of lane 8, with horizontal rotation.

• The “Total Glut 1” strip of Fig. 6 appears to have been previously published, with contrast and sharpness adjustments, as lanes 3–9 of the IR strip in Fig. 5A of the following article:

  • ∘ Caruso et al. J Biol Chem 1999;274:28637–28644. DOI: https://doi.org/10.1074/jbc.274.40.28637. PMID: 10497232

• In Fig. 8B, lanes 3 and 4 appear to be duplicates.

The Panel contacted the corresponding author to inform him of these concerns and to request an explanation. Replying on behalf of all of the authors, the corresponding author explained that the original autoradiographs for the figures in question were no longer available. The author instead provided original autoradiographs of duplicate experiments to support the reliability of the data and conclusions presented in the article.

However, the ESP considered the author's provision to be inconclusive, and because the authors were not able to provide the original data for the figures cited above, the Panel remains concerned about the reliability of data presented in this article.

Therefore, the Panel has contacted the corresponding author’s institution, Università degli Studi di Napoli Federico II, Naples, Italy, to request an institutional investigation of the issues cited above. Diabetes will make a final decision on the publication status of this article after the journal obtains more information on the reliability of the data and conclusions presented in the article.

Diabetes is a member journal of the Committee on Publication Ethics (COPE) (publicationethics.org). As such, the editors of the journal and the ESP refer to COPE’s guidelines and recommendations when reviewing such matters.

• © 2017 by the American Diabetes Association.