Development was made aware by a reader of potential duplication of data in Fig. 2A, Fig. 5C, Fig. 6 and Fig. 7A of Development (2004) 131, (doi:10.1242/dev.01050).
The journal contacted the authors who said that some of the bands in western blots were duplicated during figure compilation. After discussion with Anthi Karaiskou and Catherine Jessus, Development referred this matter to Université Pierre et Marie Curie (UPMC, now Sorbonne Université), who investigated and cleared the authors of any wrongdoing. The UPMC committee decided that the conclusions of the paper were not affected by the errors and recommended correction of the paper (full reports available at: http://www2.cnrs.fr/sites/communique/fichier/rapport_conclusions.pdf and http://www2.cnrs.fr/sites/communique/fichier/rapport_analyse_detaillee.pdf). Development's editorial policies state that: “Should an error appear in a published article that affects scientific meaning or author credibility but does not affect the overall results and conclusions of the paper, our policy is to publish a Correction…” and that a Retraction should be published when “…a published paper contain[s] one or more significant errors or inaccuracies that change the overall results and conclusions of a paper…”. Development follows the guidelines of the Committee on Publication Ethics (COPE), which state: “Retraction should usually be reserved for publications that are so seriously flawed (for whatever reason) that their findings or conclusions should not be relied upon”. The standards of figure assembly and data presentation in this paper fall short of current good scientific practice. However, given that the investigating committee at UPMC declared that the conclusions of the paper were not affected by the errors, the appropriate course of action – according to COPE guidelines – is to publish a Correction, which Development has made as detailed as possible.
Readers should note that the policy of the UPMC is that authors should retain original data for 10 years; the paper falls outside this period. The authors were unable to find all the original data, but replicates of experiments carried out at the same time showing the same results were found for most blots and several new figure panels have been assembled.
In Fig. 2A, no data for the cyclin B2 blot could be found. The authors say that as the same results are also shown in Fig. 1B, and Figs 3 and 6, the cyclin B2 blot can be removed without affecting the conclusions. The new Fig. 2A is shown below. Development has not seen the original data for these results.
Expression of the regulators of Cdc2 activation during oogenesis. (A) Prophase oocytes at stage IV (750-800 μm), stage V (900-11,000 μm) and stage VI (≥1200 μm) were incubated or not in the presence of progesterone and collected 18 hours afterwards. Oocyte extracts were western blotted with antibodies against the active phosphorylated form of MAPK (P-MAPK), Mos, MAPK, the Thr161-phosphorylated form of Cdc2 (P-Thr161-Cdc2), Plkk1 and Myt1.
Expression of the regulators of Cdc2 activation during oogenesis. (A) Prophase oocytes at stage IV (750-800 μm), stage V (900-11,000 μm) and stage VI (≥1200 μm) were incubated or not in the presence of progesterone and collected 18 hours afterwards. Oocyte extracts were western blotted with antibodies against the active phosphorylated form of MAPK (P-MAPK), Mos, MAPK, the Thr161-phosphorylated form of Cdc2 (P-Thr161-Cdc2), Plkk1 and Myt1.
Fig. 4B had unmarked splicing that the authors would like to correct. Original data could not be found for these blots but results from a replicate experiment carried out at the same time are shown.
Okadaic acid is unable to induce MPF auto-amplification in stage IV oocyte extracts. Stage IV and stage VI oocyte extracts were incubated in the presence (+) or in the absence (–) of 1 μM okadaic acid (OA) and an ATP-regenerating system for 3 hours. (B) Western blots revealed with antibodies against the active phosphorylated form of MAPK (P-MAPK), Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2).
Okadaic acid is unable to induce MPF auto-amplification in stage IV oocyte extracts. Stage IV and stage VI oocyte extracts were incubated in the presence (+) or in the absence (–) of 1 μM okadaic acid (OA) and an ATP-regenerating system for 3 hours. (B) Western blots revealed with antibodies against the active phosphorylated form of MAPK (P-MAPK), Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2).
For Fig. 5C, most of the original blots were found and the corrected figure panel is shown below. Note that original data were not found for the Cdc2 kinase activity, so this autoradiogram has been removed. The authors state that this does not affect the conclusions as Cdc2 activity is reflected by its tyrosine phosphorylation level and the graph in Fig. 5B. Lines indicating where the blots in Fig. 5A have been spliced have also been added; however, Development has not seen the original data for Fig. 5A.
Presence of Plk1 restores MPF auto-amplification induced by cyclins or okadaic acid in stage IV oocyte extracts. (A) Stage IV and stage VI oocyte extracts were incubated in the presence or in the absence of either His-cyclin B1 (B1) or GST-cyclin A (A) and ATP for 3 hours. They were western blotted with antibodies against Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2). (B) Stage IV and stage VI oocyte extracts were incubated for 3 hours in the presence of increasing amounts of human His-cyclin B1 and were then assayed for H1 kinase activity of Cdc2. (C) Stage IV oocytes were injected with human Plk1 mRNA. After overnight incubation, oocyte extracts were prepared and supplemented with 1 μM okadaic acid (OA) or His-cyclin B1 (B1) and ATP. Three hours later, extracts were western blotted with antibodies directed against Myc (indicating the presence of the Myc-tagged Plk protein), Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2).
Presence of Plk1 restores MPF auto-amplification induced by cyclins or okadaic acid in stage IV oocyte extracts. (A) Stage IV and stage VI oocyte extracts were incubated in the presence or in the absence of either His-cyclin B1 (B1) or GST-cyclin A (A) and ATP for 3 hours. They were western blotted with antibodies against Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2). (B) Stage IV and stage VI oocyte extracts were incubated for 3 hours in the presence of increasing amounts of human His-cyclin B1 and were then assayed for H1 kinase activity of Cdc2. (C) Stage IV oocytes were injected with human Plk1 mRNA. After overnight incubation, oocyte extracts were prepared and supplemented with 1 μM okadaic acid (OA) or His-cyclin B1 (B1) and ATP. Three hours later, extracts were western blotted with antibodies directed against Myc (indicating the presence of the Myc-tagged Plk protein), Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2).
In Fig. 6, original blots were found for all panels except P-MAPK and the corrected figure with lines indicating splices is shown.
Stage IV and stage VI oocytes were stimulated by progesterone or injected with either GST-cyclin B or Xenopus Mos protein or both GST-cyclin B and Mos. Oocytes were collected and western blotted with antibodies against cyclin B2, the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2) and Rsk.
In Fig. 7A, replicate results from the same experiment were found. No original data were found for the H1 kinase activity, so this has been removed. The authors state that absence of these data does not affect the conclusions because Cdc2 activity is reflected by its tyrosine 15 phosphorylation level. Lines indicating where the blots in Fig. 7B have been spliced have also been added. The new figure is shown here.
In vivo rescue of MPF auto-amplification by Plk1 in stage IV oocytes. (A) Stage IV oocytes were injected or not with Plk1 mRNA. After overnight incubation, they were either incubated in the presence or not of progesterone, or injected with His-cyclin B1. Stage VI oocytes were used as control. Extracts were western blotted with antibodies against Cdc25, the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2), Myc (indicating the presence of the Myc-tagged Plk protein), Myt1 and the active phosphorylated form of MAPK (P-MAPK). (B) Stage IV oocytes were injected or not with Plk1 mRNA. After overnight incubation, they were either incubated in the presence or not of progesterone (Pg), or injected with okadaic acid (OA). Extracts were western blotted with antibodies against Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2).
In vivo rescue of MPF auto-amplification by Plk1 in stage IV oocytes. (A) Stage IV oocytes were injected or not with Plk1 mRNA. After overnight incubation, they were either incubated in the presence or not of progesterone, or injected with His-cyclin B1. Stage VI oocytes were used as control. Extracts were western blotted with antibodies against Cdc25, the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2), Myc (indicating the presence of the Myc-tagged Plk protein), Myt1 and the active phosphorylated form of MAPK (P-MAPK). (B) Stage IV oocytes were injected or not with Plk1 mRNA. After overnight incubation, they were either incubated in the presence or not of progesterone (Pg), or injected with okadaic acid (OA). Extracts were western blotted with antibodies against Cdc25 and the Tyr15-phosphorylated form of Cdc2 (P-Tyr-Cdc2).
As a result of corrections to these figures, readers of Development (2004) 131, 1543-1552 (doi:10.1242/dev.01050) should ignore reference to H1 kinase activity on p. 1549. The second paragraph should now read: ‘The high H1 kinase activity generated by cyclin B1 addition in the presence of Plk1 indicates that, despite the partial phosphorylation of Cdc2, the cyclinB1-Cdc2 neocomplexes are mainly active (Fig. 5C).’ Text in the fourth paragraph should read: ‘Constitutively active Plk1 expression did not allow stage IV oocytes to respond to progesterone, as indicated by the absence of Cdc25 and Myt1 electrophoretic shift and the maintenance of Tyr15 phosphorylation of Cdc2 (Fig. 7A).’
The authors apologise to the journal and readers for these errors.
Development refers readers to other notices related to the UPMC investigation, published in our sister journal, Journal of Cell Science:
