CDKN1B and leukemia: To confirm the association of MLL suppression with PI sensitivity and p27 expression in MLL leukemia, we knocked down the MLL gene in SEM cells and observed that MLL depletion significantly decreased the sensitivity of SEM cells to bortezomib (Fig. 2a, b), reduced the expression of p27 and suppressed the induction of p27 by bortezomib (Fig. 2c).