Table 2.

Substrate-drugs of ABCB1 co-treated with WYE-354 decreased the survival rates of drug-selected cells.

Treatment	IC50 ± SD a (RF b) (μM)
	KB-3-1	KB-C2
Doxorubicin	0.019 ± 0.004 (1.00)	1.549 ± 0.158 (81.52)
+WYE-354 (0.3 µM)	0.016 ± 0.004 (0.84)	0.983 ± 0.140 (51.74) *
+WYE-354 (1 µM)	0.016 ± 0.004 (0.84)	0.563 ± 0.164 (29.63) *
+Verapamil (1 µM)	0.013 ± 0.005 (0.68)	0.095 ± 0.012 (5.00) *
Paclitaxel	0.006 ± 0.001 (1.00)	1.432 ± 0.075 (238.67)
+WYE-354 (0.3 µM)	0.006 ± 0.002 (1.00)	0.736 ± 0.069 (122.67) *
+WYE-354 (1 µM)	0.005 ± 0.001 (0.83)	0.296 ± 0.041 (49.33) *
+Verapamil (1 µM)	0.004 ± 0.001 (0.67)	0.075 ± 0.010 (12.50) *
Cisplatin	1.472 ± 0.351 (1.00)	1.139 ± 0.060 (0.77)
+WYE-354 (0.3 µM)	1.498 ± 0.054 (1.02)	1.148 ± 0.232 (0.78)
+WYE-354 (1 µM)	1.214 ± 0.061 (0.82)	1.187 ± 0.037 (0.81)
+Verapamil (1 µM)	1.314 ± 0.063 (0.89)	1.462 ± 0.306 (1.02)

^a IC₅₀ values are represented as mean ± SD from three independent experiments in triplicate. ^b The resistance fold (RF) was calculated by dividing the IC₅₀ values in KB-3-1 or KB-C2 cells by those in KB-3-1 cells without WYE-354 or verapamil. * indicates p < 0.05.