hPMR1 stimulation of cell motility. Triplicate cultures of MCF-7 cells that were stably transfected with plasmids expressing tetracycline repressor protein and Flag-hPMR1 under a tetracycline-inducible promoter were treated for 24 h ±doxycycline prior to scoring the monolayer. Mitomycin C was added 4 h prior to the start of the motility experiment to block replication, and the same three fields from each set of cultures were photographed at each time point. Changes in the distance across the gap were used to calculate the percentage of closure as a function of time, and the data represent the mean ± SD obtained at each time point; differences between treatment groups were determined by Student's t-test or two-way ANOVA. There was no difference at times 0, 4, and 8 h, but at later time points, differences in the degree of gap closure were statistically significant, with P < .0001. The right panel is a Western blot of protein recovered at the end of the experiment probed with anti-Flag antibody.
