Western blot analysis of caspases −3, -8, and −9 and cytochrome c in U937 cells treated with MG132, Doxorubicin (DOX) or MG132 + DOX. U937 cells were cultured and treated with MG132 (1 μM), DOX 1 μM, or with MG132 + DOX. After 24 h, the cells were harvested and lysed. Equivalent amounts of individual lysates were placed onto 10% SDS gradient polyacrylamide gels for electrophoresis and then were electrotransferred onto Immobilon-P PVDF membranes. A representative study is shown. Relative density was calculated using IMAGEJ ver.1.46r software.