Figure 5.

Breast Cells Are More Resistant to Doxorubicin Than Lung Cells

(A) Cell viability response to equal intracellular amounts of doxorubicin. After 48 h of doxorubicin treatment, intracellular doxorubicin fluorescence was determined by fluorescence-activated cell sorting (Figure S12). The intracellular doxorubicin levels (arbitrary units) were plotted against the cellular viability (as determined by MTT assay) (n = 3). Error bars represent the SD. Regression analysis was used to test if the slope and intercept were different.

(B) Relative change of Chk1, Chk2, p53, and p21 dynamics after doxorubicin treatment in breast and lung cells. Depicted is the average relative expression per treatment (n = 4–6) normalized to the maximum value per graph. Error bars represent the SEM. Two-way ANOVAs were used to test if a protein was differentially expressed in breast versus lung cells. See also Figure S13.

(C) Comparison of model simulations to the experimental data in response to doxorubicin treatment. To compare with the corresponding experimental data, the model simulation data were scaled as relative values (normalized to the maximal values in breast and lung cells) and depicted as blue lines. Data from individual blots are depicted as “+.” The average values are shown as red circles. Note that some data points with the same values appear overlapped in this scatterplot.