Background

Nature’s editors issued an Editorial Expression of Concern noting that two bands in Figure 1b of a 1999 paper on the creation of human tumor cells may be duplicated. They also stated that the paper’s remaining data continue to support its main conclusions. The notice asks readers to exercise caution when interpreting specific data while distinguishing that concern from the editors’ assessment of the paper’s overall conclusions.

The paper, “Creation of human tumour cells with defined genetic elements,” was published in Nature on July 29, 1999. The Editorial Expression of Concern was published on April 15, 2026. It is a notice alerting readers to concerns about a figure in an existing paper, rather than a study reporting new experimental results.

Key findings

The issue identified by the editors is the possibility that two bands in Figure 1b are duplicated. The notice explains that the original data were unavailable because of the age of the paper. It does not state that duplication has been confirmed, nor does it characterize the absence of original data as evidence of research misconduct. The notice alone does not establish the cause of the possible duplication or how the image was prepared.

Splicing within the gel image in the same figure was also noted. However, the editors explicitly stated that such splicing was permitted at the time. The possible duplication of the two bands and the gel splicing should be considered separately. Mentioning the splicing without explaining that it was permitted at the time would fail to convey the context of the editors’ assessment accurately.

The editors’ position on the main conclusions is also clear: the paper’s remaining data continue to support them. Alongside that assessment, the editors advised readers to interpret the data identified above with caution. The notice flags concerns about a specific figure without extending them into a declaration that the paper’s overall conclusions are invalid.

Implications and outlook

When reading or citing the paper, readers should consider both the concerns about Figure 1b and the editors’ assessment of the main conclusions. Omitting the figure issues solely because the main conclusions remain supported—or, conversely, describing concerns about a specific figure as a rejection of the paper’s overall conclusions—would miss the purpose of the notice.

The notice does not discuss failed replications by independent research teams, PubPeer discussions, institutional investigations, or whether the paper will be retracted in the future. There is therefore no basis for presenting these as reasons for this notice or as confirmed follow-up procedures. The notice available for this review also does not provide material to assess the original paper’s specific genetic elements, cell models, or experimental conditions. What can be established is the possible duplication of two bands in Figure 1b, the unavailability of original data, the gel splicing permitted at the time, and the editors’ assessment that the remaining data support the main conclusions.

Further details are available in the Nature Editorial Expression of Concern.