Researchers have pioneered a novel method to track the dynamic evolution of cancer cell resistance to therapies by integrating genetic barcoding with quantitative phenotypic analysis. This approach, published in Nature Communications, allows lineage tracing of tumor cell populations with uniquely tagged DNA identifiers, revealing complex adaptation patterns under drug pressure. Their findings demonstrate that resistance arises not only from the expansion of pre-existing clones but also through emergent resistant phenotypes, highlighting plasticity within tumor ecosystems. This methodology offers precise tracking of tumor heterogeneity and evolution, potentially informing more effective, adaptive therapeutic regimens to overcome resistance and improve patient outcomes.