Sensitization of HUT78 cells to DAB389IL-2 (denileukin diftitox) by depsipeptide. HUT78 cells were first exposed to depsipeptide or control treatment for 48 hours; denileukin diftitox (DAB389IL-2) was then added for 72 hours. Cytotoxicity assay was performed as described in “Materials and methods.” Error bars indicate standard error of triplicates.