Sensitization to TRAIL-induced cell death and induction of DR5 expression by nutlin3a are significantly diminished in p53-knockdown cells. OCI-AML3vec and OCI-AML3p53shRNA cells were treated with TRAIL, nutlin3a, or both agents. p53 and DR5 protein levels were determined by Western blotting and cell death was determined by annexin V/PI staining at 24 hours. Solid lines with solid marks represent OCI-AML3vec cells, and dashed lines with open marks represent OCI-AML3p53shRNA cells. Error bars represent SE.