Clarification of data used in three studies on MCA-induction of sarcoma in mice

To the editor:

This letter is to clarify the relationship between the primary data reported in Figure 4A of Street et al¹  and that previously published in Figure 3 of Smyth et al²  and Figure 3A of Smyth et al.³  The data in these figures were all derived from the same series of 9 large experiments performed over a 2-year period (1998-2000; Table S1, available on the Blood website; see the Supplemental Materials link at the top of the online article). Practically, and for ethical reasons, it was not possible to compare all the groups within any individual experiment and thus, to compare various strains of mice, data were pooled from separate experiments and some cohorts of mice were used in more than one Figure. Importantly, the preparation of carcinogen used in these experiments was the same, prepared several weeks before any of the experiments began, and the reproducibility between experiments was high.