KIT and leukemia: Using primary c-kit+ HSPCs from this Prmt1flox/flox Cre-ER mouse for RTTA, we observed an even more prominent suppression of MLL-GAS7 transformed cells both in vitro (Figures S1I and S1J) and in vivo (Figure 1J) whereby none of the mice developed leukemia upon Prmt1 deletion.