Dose-dependent mitotic arrest of type B cells during nocodazole treatment. (a–d) After a 24-hour treatment with various nocodazole concentrations, adherent and nonadherent MDA-MB-468 (a), T47D (b), or MCF-7 cells (d) were combined and examined by fluorescence microscopy. (c) HMECs (passages 2–4) were treated for 24 hours with diluent (i), 100 nM paclitaxel (ii), or nocodazole at 83, 167, 1,200, and 3,000 nM (iii–vi, respectively). (e) After a 24-hour treatment with various concentrations of paclitaxel, adherent and nonadherent MDA-MB-468 cells were combined and examined by fluorescence microscopy. (f–h) Whole-cell lysates from MDA-MB-468 cells treated with the indicated concentration of nocodazole for 24 hours (f), or the indicated cell lines treated with 1 μM nocodazole for 24 hours (g and h) were subjected to SDS-PAGE followed by blotting for p21 and PARP (which served as a loading control). Error bars show ± one SD from three independent experiments (a, b, d, and e), or ± range from two (c) independent experiments.