Simultaneous inhibition of XIAP and activation of p53 improves sensitization of AML cells to TRAIL-induced cell killing. OCI-AML3 cells were treated with TRAIL, 1396-11, nutlin3a, TRAIL plus 1396-11, TRAIL plus nutlin3a, or TRAIL plus 1396-11 and nutlin3a for 24 hours. Cell death was assessed by annexin V/PI staining. N3a indicates nutlin3a; TR, TRAIL. Error bars represent SE.