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. 2011 Aug 30;6(8):e24312. doi: 10.1371/journal.pone.0024312

Figure 2. Effect of cyclin B1 knockdown on the development of nocodazole (Noco)-induced prometaphase arrest in MCF-7 cells.

Figure 2

A. Cells were transfected with cyclin B1 siRNA (si-cyclin B1) and the negative control siRNAs (si-Con), 24 h later, cells were exposed to 250 nM nocodazole for additional 12 h. Then the whole cell lysates were analyzed for the levels of cyclin B1 and Cdc2by Western immunoblotting. B. Relative protein levels of cyclin B1 and Cdc2 are calculated according to densitometry readings, which are then normalized according to the corresponding readings for the GAPDH protein bands. Each value is mean ± S.D. from three replicate determinations. * P<0.05, ** P<0.01 versus vehicle-treated control; # P<0.05, ## P<0.01 versus nocodazole treatment. C. Cells were transfected with si-cyclin B1 or siRNA negative control and then further treated with nocodazole (250 nM) for 12 h. Cells with cyclin B1 knockdown were analyzed using immunofluorescent staining for cyclin B1. Representative photographs were taken using a fluorescence microscope (original magnification, ×200) or a phase contrast (PC) microscope (×200). D. Quantitative data on prometaphase-arrested cells. Each bar is a mean ± S.D. value from three separate experiments. * P<0.05, ** P<0.01 versus the vehicle-treated control; # P<0.05 versus nocodazole treatment. E. The DNA content of cells was analyzed using flow cytometry as described in the Material and Methods section.