Figure 4.
Inhibiting JNK activation abrogates arsenic trioxide-induced apoptosis in NB4 cells. (A) NB4 cells were treated with 10 μM As2O3 alone or in combination with 1 μM dicumarol for 16 hours. An immune complex kinase assay was performed to ensure inhibition of JNK1 at this dose of dicumarol. (B) NB4 cells were either left untreated (
) or were treated for 3 days with 0.5 μM As2O3 (left panel) or 0.01 μg/mL doxorubicin (right panel) alone (▪) or in combination with 1 μM dicumarol (*), which was replenished daily. Growth inhibition was assessed by counting trypan blue-excluding cells, which always made up more than 97% of the total cells examined. Each data point shown represents an average of 3 independent replicates, and standard deviation error bars are shown.