Induction of apoptosis by HOXA9 suppression is significantly correlated with the presence of the MLL-fusion oncogene. (A) Analysis of cell viability at day 7 after HOXA9 shRNA transduction in a larger panel of 11 AML/ALL cell lines (6 MLL-rearranged; 5 MLL-wild-type) showing significantly higher apoptosis induction in MLL-rearranged cells with all 4 HOXA9shRNA constructs. (B) Independent analysis in a panel of 17 AML/ALL cell lines (7 MLL-rearranged; 10 MLL-wild-type) further demonstrated a significant correlation between cell number and baseline HOXA9 expression after shRNA-mediated suppression, with the greatest effect in cell lines expressing the highest HOXA9 levels (R = −0.8: P = .001; ●, MLL-rearranged cell lines; , MLL-wild-type cell lines).