RNF20 and acute lymphoblastic leukemia: Interestingly, while our results imply that MLL is the main mediator of the observed effects of bortezomib on cell cycle, which partially mediates the effect of H2Bub depletion in MLL-rearranged ALL cells, previous reports showed that the depletion of RNF20 but not MLL leads to inhibition of cell proliferation in MLL-rearranged AML cells, suggesting the effect of H2Bub depletion in AML cells is not mediated by MLL [13, 50].