DOT1L and leukemia: Given that cell lines were exposed to compounds for only 3 days and DOT1L inhibitors are well documented to act very slowly in MLL-rearranged leukemia [14, 16], we validated and extended this observation in a panel of 14 MM cell lines using growth assays with a duration of 2-3 weeks (Figure 1A and Supplementary Figure 1A and 1B).