Cell lines used in many laboratories are often not what they are claimed to be, resulting in misleading research articles. A well-characterized case of cross-contamination is the widely used human cancer cell line called HeLa. In the Early Edition of the Proceedings of the National Academy of Sciences, Masters et al. describe the use of forensic techniques to expose culprit samples. Short tandem repeat (STR) profiling is a simple PCR-based technique that generates results in the form of a standard numerical code for lengths of polymorphic loci. Masters et al. analysed 253 human cell lines, collected from international cell banks and cancer research institutes, to demonstrate the feasibility of wide-scale STR profiling to detect cross-contamination. The authors suggest that STR profiling (at a cost of only $200 per cell line) could be used to create an international reference standard for human cell lines and they propose that a...