ABCB1 and lymphoma: Both compounds were tested on human MDR1 gene-transfected mouse lymphoma cells, where ID50 for doxorubicin is 0.35 μg/mL, ID50 for 2 is 4.58 μg/mL, and ID50 for combination of both is 0.095 μg/mL, with a fractional inhibitory index of 0.292 [10].