The Reproducibility Project: Cancer Biology aims to replicate a number of landmark studies in the field of tumor biology published between 2010 – 2012. The latest replication attempt was published on March 12^thin eLIFE and focused on a publication from 2011 by Liu et al. The attempt to replicate the major findings was unsuccessfully. The publication by Yan et al. reported increased miR-34a expression in CD44⁺derived prostate cancer cells, whereas the original report showed decreased levels. Similar opposing results were obtained in respect to tumor growth: the replication study did not reveal changes in tumor size whereas the original study showed decreased growth after miR-34a overexpression. In line with these results, the mechanism from the original paper, the decreased expression of CD44 by miR-34a binding to a 3’UTR of CD44, could not be replicated .

Once again, this unbiased replication study shows the importance of replicating findings and increasing the internal as well as external validity before advancing a project and the start of resource-consuming translational programs.