PROM1 and leukemia: To assess whether PRC2 silencing is a common mechanism for PROM1 regulation in CD133-negative leukemia and not restricted to MLL-AF9 AML, we analyzed RCH-ACV (non-MLLr Pre-B-ALL) and ML-2 (MLL-AF6 AML) cell lines, which do not express PROM1 or present CD133 on the cell surface (Fig. 1a and Supplementary Fig. 1a).