MLLT3 and leukemia: Interestingly, we found that the level of H3K79me, the key downstream symbol of classical pathway of MLL-AF9, was equivalent in Celf2 KO + MA9 and MA9 AML cells (Figs. 5E and S5B) [39–42], while the mTORC1 signaling pathway was activated only in Celf2 KO + MA9 but not in Celf2 WT + MA9 leukemia cells (Fig. 5).