ABCB1 is only expressed in the doxorubicin resistant breast cancer cell line and is inversely correlated with the expression of miR-203 and miR-200c The KCR resistant subline expresses both ABCB1 and ABCC1 (Multidrug resistance-associated protein, MRP-1) genes and its parental cell line MCF-7 only expresses MRP-1 (Joseph Molnar, personal communication). This evidence concerns the gene ABCC3 and breast carcinoma.