Effect of pervanadate on morusin-mediated STAT3 inhibition and apoptosis in human prostate cancer cells. A. DU145 and M2182 cells were treated with morusin for 6 hours. B. DU145 and M2182 cells were treated with pervanadate (0.5 μM) and morusin (30 μM) for 6 hours. A and B. Cell lysates were subjected to Western blotting with the indicated antibodies. β-actin was used as an internal control. C. DU145 and M2182 cells were treated with pervanadate (0.5 μM) and morusin (30 μM) for 24 hours. The TUNEL and DAPI staining were analyzed by confocal microscopy (C, control; M, morusin; and P, pervanadate). Scale bar, 70 μm. Quantitative analysis of TUNEL positive cells are expressed as relative amount of the treated cells compared to that of the mock-treated control. Data in the graphs are presented as the mean ± SEM (*, P < 0.05; and **, P < 0.01 versus morusin-treated control).