AFF1 and acute lymphoblastic leukemia: PROM1 KO in CRISPRKMT2A::AFF1 ALL led to a significant loss of CD133 expression by flow cytometry (Figure 2F), and an increased proportion of cells in sub-G1 phase 72 hours after KO (Figure 2G; 22.8% vs 7.7%, P = .02), suggesting increased apoptosis in PROM1 KO cells.