Table 2. Pharmacologic inhibition of MRP4 increases sensitivity to 6-MP.

Pharmacologic Treatment	μM	Fold Sensitizationa
MDA-MB-231
MK571	50	2.94	*
MDA-MB-436
MK571	25	1.47	*
Tyrphostin AG 1478	10	2.86	**
BT549
MK571	50	1.76	**
Tyrphostin AG 1478	10	4.83	**

^aSensitization by MRP4 inhibitors relative to vehicle treatment

* p < 0.05, ** p < 0.01