HBB and cancer: Interestingly, in two patients, only a minority of cells (5–10% of total cells) were identified as cancer progenitor cells with hyperproliferation features (Fig 3A), and they exhibited hybrid features of mature erythroid cells (e.g., expressing the genes HBB and GYPA for hemoglobin β and glycophorin A, respectively) and stem cells (e.g., expressing SOX4).