Leukemic blasts are organized into a hierarchical structure of differential capability for stem cell–like proliferation and renewal, with HSPC-like cells at the root of a tree shown for descriptive purposes, and more differentiated lineage-like blasts reside as leaves on the tree. Chen et al found that these HSPC-like blasts are enriched for stem cell transcriptional phenotypes. These stem-cell cells are disproportionately resistant to chemotherapy. Figure created with BioRender.com.