To further understand the regulation of PROM1 by MLL-AF4 we explored the chromatin landscape at PROM1 by ChIP-seq and ATAC-seq in SEM and RS4;11 cells and primary blast cells from an MLL-AF4 ALL patient, which we confirmed were CD133-positive (Supplementary Fig. 1e, upper panels). Here, AFF1 is linked to acute lymphoblastic leukemia.