A Diagram of procedure for mouse tumor model. First, 2 × 105 EMT6 cells were transplanted into mammary fat pads of BALB/c mice. Seven days after transplantation, tumor-bearing mice were divided into 3 groups and treated with oleandrin at 0.3 and 0.6 mg/kg intraperitoneal for 7 days. Mice treated with PBS were used as control. B Tumor volume was measured every day and quantified as 0.5 × length × width × width. The volume was expressed as mean ± SD (n = 5) and represented as tumor volume–time curves to show (*p < 0.05, **p < 0.01 vs. control.). C After 7 days of administration, mice were sacrificed, and tumors were weighted. The representative tumors were shown. D Tumor weight in each group was expressed as mean ± SD (n = 5, **p < 0.01 vs. control).