The cell of origin and LSC-switching model. (A) Multiple cells, such as HSC1, HSC2, HPC1, HPC2, and HPC3 cells, serve as the cell of origin. After leukemia is initiated, the leukemia pool is expanded and maintained through back-and-forth switching among (B) heterogeneous LSCs (for instance, LSC1 and LSC2). ★★★Transduced cells by MA9 or ICN-1 virus.