Modulation of doxorubicin-induced expression of the multidrug resistance gene in breast cancer cells by diltiazem and protection against cardiotoxicity in experimental animals

Effect of DOX and/or DIL treatment on cell cycle phase distribution of MCF-7 cells. Cell cycle distribution was analyzed by exposing the cells to drugs for 48 h, then staining with PI. a Control, b cells treated with 20 μg/ml DIL, c cells treated with 0.25 μg/ml DOX, d cells treated with 0.25 μg/ml DOX and 20 μg/ml DIL, e cells treated with 1 μg/ml DOX, f cells treated with 1 μg/ml DOX and 20 μg/ml DIL. The experiment was repeated twice each one in duplicat