Female BALB/c mice (age: 8 weeks, weight: 20−22 g) were purchased from the Army Medical University Animal Center (Chongqing, China) under protocols approved by the Animal Ethics Committee of the Army Medical University. The study design and all animal experimental procedures were performed in accordance with the Guide and Use of Laboratory Animals (Institute of Laboratory Animal Resources), and the IACUC for Medical Research at Army Medical University. Tumor-bearing mice were prepared by subcutaneously injecting a suspension of 12×104 4T1 cells in PBS (100 μL) into the right lateral hind limbs of female mice.