Expression of PML/RAR-α protein inpml/RAR-α–introduced COS-7 cells (A) and NB4 cells (B) that had been treated with TT or 9CTT. (A) COS-7 cells were transfected with a pml/RAR-α expression vector, pCMX-PML-RAR-α, by lipofection and treated with various concentrations of TT or 9CTT for 2 days. Total cellular protein from 105 cells was separated on a 10% sodium dodecyl sulfate-polyacrylamide gel and blotted onto an Immobilon membrane. The PML/RAR-α protein was detected with a rabbit polyclonal antibody to RAR-α and visualized with a biotin-avidin-alkaline phosphatase system. The amount of the fusion protein was quantified with a densitometer and compared with that in the untreated cells. Two additional experiments showed similar results. (B) NB4 cells (2 × 105/mL) were treated with TT or 9CTT for 4 days and the crude nuclear extracts (20 μg) were separated on a gel. The fusion protein was detected with an anti-PML antibody.
