In this study, we plan to determine the roles and mechanism of TBX15/miR-152/KIF2C pathway on DOX resistance, and whether PKM2 is involved; to test whether TBX15 downregulation is sufficient to induce DOX resistance in breast cancer; and to define role and mechanism of KIF2C and PKM2 in mediating DOX resistance. The gene discussed is PKM; the disease is breast cancer.