Enhancing the precision of genetic lineage tracing using dual recombinases

Genetic cell-lineage tracing studies in mice are crucial for delineating the contribution of stem and progenitor cells to different cell types, both in disease states and after regenerative therapy. He et al. have developed new genetic lineage-tracing systems that provide more definitive results than the commonly used Cre-based system and show that this new technology can resolve current controversies in the field, as demonstrated by lineage-tracing studies in the heart and liver.