INPP4B siRNA sensitizes AML to chemotherapy. (A) KG-1 or (B) OCI-AML3 cells were cultured for 48 hours prior to being treated with 5 μM or 25 μM ara-C for 24 hours, and viability was measured by using flow cytometric enumeration of propidium iodide–negative cells. Results represent the mean ± SD of 2 independent experiments. (A) KG-1 or (B) OCI-AML3 cells were transduced with siRNAs targeting either INPP4B (INPP4B siRNA-1 or siRNA-2) or a scrambled control for 12 hours and were cultured for 48 hours prior to cytotoxic treatment as above. Similar experiments were performed in primary AML samples (C) AML 31 and (D) AML 32 shown to have high INPP4B expression (AML 31 [supplemental Figure 10D] and AML 32 [supplemental Figure 10E], confirming sensitization of primary AML blasts to ara-C after INPP4B siRNA targeting.