Table 1.

Fifty percent inhibitory concentration (IC₅₀) values and Hill coefficient of selected inhibitors on apparent AP-to-BL and BL-to-AP permeability, and efflux ratio (ER) of paclitaxel in Caco-2 cell monolayers.

Inhibitor	IC50 (nM)			Hill Coefficient
	P app,AB	P app,BA	ER	P app,AB	P app,BA	ER
Cyclosporin A	1973 ± 21	1820 ± 126	502 ± 126	−1.63 ± 0.09	2.18 ± 0.39	1.63 ± 0.20
GF120918	319 ± 30	239 ± 97 a	60 ± 21	−1.28 ± 0.09	1.63 ± 1.28	1.66 ± 0.51
XR9576	234 ± 61	64 ± 40	46 ± 19	−2.10 ± 0.64	18.4 ± 4.76	3.41 ± 0.28
LY335979	427 ± 52	107 ± 59 a	115 ± 22	−2.23 ± 0.31	0.57 ± 0.35	1.71 ± 0.41
WK-X-34	935 ± 33	501 ± 132 a	214 ± 113	−10.7 ± 6.00	1.29 ± 0.42	2.07 ± 1.22
VX-710	2680 ± 53	4496 ± 84	871 ± 277	−1.84 ± 0.07	1.08 ± 0.60	1.68 ± 0.38
OC144-093	n.c.	n.c.	n.c.	n.c.	n.c.	n.c.

^a Data from our previous report [31]. n.c., not calculated. IC₅₀ on P_app,AB: the inhibitor concentration to achieve 50% increase of P_app,AB of paclitaxel. IC₅₀ on P_app,BA: the inhibitor concentration to achieve 50% decrease of P_app,BA of paclitaxel. IC₅₀ on ER: the inhibitor concentration to achieve 50% decrease of ER of paclitaxel (Figure S3). Data are represented as mean ± S.D. for three experiments using different wells from a single passage of Caco-2 cells.