In this study, we detected three mitochondrial proteins (CPS1, ATAD3A/ATAD3B, and ABHD11) and one lysosomal protein (cathepsin D) with different expressions in paclitaxel-resistant MCF7/PacR breast cancer cells compared to paclitaxel-sensitive MCF7 breast cancer cells. This evidence concerns the gene CTSD and breast carcinoma.