Figure 1.

Characterization of Ba/F3 pTET-On p210 cells. (a) Cells were either grown in interleukin 3 (IL3) (lane 1), washed free of IL3 and treated with doxycycline (1 μg/ml, lane 2 or 10 μg/ml, lane 3) for 24 h or treated with doxycycline and IL3 for 24 h (1 μg/ml, lane 4 or 10 μg/ml, lane 5). Cells were harvested, washed and lysed. Lysates were examined for the expression of BCR/ABL by western blotting with anti-ABL antibody. (b) Cells were grown in IL3 (white bars), doxycycline alone (gray bars) or both (black bars) for 24 h. Cells were then treated with 10 μm etoposide for 2 h, washed free of drug and re-plated at 2 × 10⁵ cells/ml. Viable cells were counted each day by Trypan blue exclusion. (c) Cells were grown in IL3 (boxes), doxycycline (triangles), both (circles) or neither (diamonds) and then treated with etoposide for 48 h at indicated concentrations. Cell survival was assayed by XTT and compared to untreated cells. (d) Cells were grown in IL3 (diamonds with solid line), no cytokine (open diamonds with hatched line) or with IL3 at a fixed dose and doxycycline at various concentrations to induce different levels of BCR/ABL expression and then treated with etoposide for 48 h at indicated concentrations. Cell survival was assayed by XTT and compared with untreated cells. Cells growing in IL3 (e) or in doxycycline to induce BCR/ABL (f) were treated with etoposide (10 μm) for 2 h, washed and allowed to recover for 48 h. Cells were treated with colcemid to arrest cells in metaphase, and metaphase spreads were prepared. a and b, abnormalities present in the parent cells; cr, chromatid break; dic, dicentric chromosome; T, translocation; tri-rad, triradial form. Also note that there is only one sex chromosome, a single × chromosome.