Genes associated with the cardiotoxicity of doxorubicin (through negative effects on mitochondrial function when converted to doxorubicinol) also have altered expression in breast tumour cells upon selection for doxorubicin resistance, including ACO1, ATPS, CYCS, and ATP2B4 (Figure 2 and Additional file 1: Table S1). This evidence concerns the gene CYCS and breast neoplasm.