TABLE 1

Doxorubicin sensitivity of MCF7-derived cell lines used in this study

AUC was derived from fraction cell survival-doxorubicin concentration plots in Fig. 3, C and D. IC₅₀ and IC₉₀ values derived from four-parameter logistic nonlinear regression curve fit presented in Fig. 3, A and B.

Cell Line	AUC	IC₅₀	95% CI	IC₉₀	95% CI
	nM	nM		nM
WT scrambled	162^{^a}	11.7	10.90–12.52	2.16	1.81–2.58
WT CK2A(−)	155^{^a}	10.6	9.459–11.90	1.46	1.08–1.98
MRP1 scramble	360^{^a}	88.6^{^b}	79.23–98.97	5.45^{^b}	3.99–7.46
MRP1 CK2A(−)	229^{^a}	24.9^{^b,^c}	21.55–28.73	1.31^{^c}	0.9036–1.885
WT	564	12.2	10.98–13.47	2.45	1.9–3.16
MRP1	1114	105.3^{^d}	97.85–113.3	12.93^{^d}	10.68–15.67
MRP1-T249A	961	101.7^{^d}	87.53–118.2	5.58^{^d,^e}	3.76–8.28
MRP1-T249E	1514	107.7^{^d}	94.61–122.6	11.67^{^d}	0.39–16.22

CI, confidence interval.
↵a AUC calculated only for data points between 0 and 1 μM to allow for comparison between the lines.
↵b Significantly different from WT scrambled control.
↵c Significantly different from MRP1 scrambled.
↵d Significantly different from WT control.
↵e Significantly different from MRP1.