Additionally, the expression of common CSC markers, such as CD133 and CD44, is not exclusive to tumorigenic cells and may also be found in normal tissue stem cells or even non-tumorigenic cancer cells.1,2 Together, these observations argue for a more nuanced and context-dependent interpretation of the CSC model that accommodates both hierarchical and stochastic mechanisms of tumorigenesis, as well as plasticity-driven adaptations. The gene discussed is PROM1; the disease is cancer.