Journal of Cell Science was made aware of similarities between several bands in western blots in Fig. 5E, Fig. 6A and Fig. 7A. The corresponding author, Roberto Perego, was not able to provide all of the original full blots concerning the published Fig. 5E and Fig. 6A, so the journal referred this matter to the Milano-Bicocca University, Italy. As there is no research integrity officer at the institute, Fulvio Magni, Professor of Biochemistry, was assigned by the Dean of the School of Medicine and Surgery in April 2016 to oversee problems related to research. Professor Magni investigated and released the following statement:
‘I have carefully checked the details of the experiments reported in Fig. 6A. Both films concerning beta-actin and Arg are missing, therefore, I could not individuate a possible explanation and ensure that the beta-actin bands used for Fig. 6A are derived from the same gel used for detecting Arg. However, it seems to me that there is no intentional alteration of the results. As the authors have several replicates, I strongly suggest the authors replace Fig. 6A with one of the other experiments in which they have both original films for beta-actin and Arg proteins. For Fig. 5E, I checked the laboratory notebook and confirm the presence of film concerning pSmad2, but the film concerning total Smad is missing. Also, in this case, I could not find any possible fraudulent explanation justifying an incorrect alignment of the two films. However, I cannot exclude a possible human unintentional mistake. I suggest that the authors replace Fig. 5E with one of the other replicates with a guaranteed alignment. The original data confirm the overall conclusions of the published paper.’
As the designated investigator at the institute found that the conclusions are sound, we are publishing this Correction with replicate blots for Fig. 5E and Fig. 6A that were obtained from the same samples at the same time. The online and PDF versions of the article have been updated and the authors apologise to readers for any inconvenience caused.