Table 3.

Uptake of radiolabeled compounds in the presence of 10 μM Verapamil

	A431		NCI/Adr
	− Verapamil	+ Verapamil*	− Verapamil	+ Verapamil
Paclitaxel (70 nM)	34.2  ± 0.8†	7‡	2.2  ± 0.2	404
pED (70 nM)	19.0  ± 0.6	82	8.3  ± 0.8	306
pEB (70 nM)	58.7  ± 2.7	2	49.0  ± 1.1	5
Paclitaxel (3.5 nM)	3.3  ± 0.1	−14	0.1  ± 0.0	188
pED (3.5 nM)	0.6  ± 0.0	174	0.2  ± 0.0	795
pEB (3.5 nM)	3.9  ± 0.1	22	4.7  ± 0.2	122

Tumor cells were incubated for 2 h with the indicated concentrations of tritiated compounds in the presence or absence, respectively, of 10 μM Verapamil. After washing, cells were solubilized and the radioactivity measured and normalized to the cell numbers. 

^*10 μM Verapamil. 

^† Mean ± SD (pmol/10⁶ tumor cells). 

^‡ Percent of additional uptake in the presence of Verapamil.