Figure 3

Regulation of desmoplakin expression in breast cancer cell lines by R5020 and epidermal growth factor (EGF). (a) T47D cells were plated in RPMI media containing 5% stripped serum. (b) ZR-75 and (c) MCF-7 cells were plated in Dulbecco's modified Eagle medium (DMEM) containing 5% stripped serum. Cells were incubated with vehicle, R5020, EGF, or R5020 plus EGF for 48 hours before preparation of total cellular extract for Western blot analysis with antibody to desmoplakin or β-actin. The graphs indicate the fold difference of desmoplakin expression compared with vehicle (set at a value of 1) following measurement of Western blot signal intensity by Kodak Image Station 440CF and 1D Image Analysis software. In each independent experiment, duplicate samples for each treatment condition were normalized to the β-actin levels. The experiment was repeated two times and the mean values from these experiments ± SEM are reported. Representative Western blots for desmoplakin and β-actin levels in each cell line are shown below the graphs. *P < 0.05 versus control (by one-way analysis of variance).