YM155 treatment inhibited growth of SK-NEP-1 xenograft tumor in nude mice. SK-NEP-1 cells were subcutaneously injected into five nude mice every group. 10 days after injection, mice were treated with PBS, DMSO, YM155 5 mg/kg and 10 mg/kg dose. During the next six weeks these mice were examined for subcutaneous tumor growth. The tumor volumes were calculated according to the following formula: volume = length × width2/2. After the last treatment, the mice were killed and the tumor weight was measured. (A) SK-NEP-1 xenograft tumors from the treatment experiment. (B) Growth curve of SK-NEP-1 cells treated with YM155, DMSO and PBS. YM155 significantly inhibited growth of SK-NEP-1 xenografts (YM155 5 mg/kg: 1.45 ± 0.77 cm3; YM155 10 mg/kg: 0.95 ± 0.55 cm3) compared to DMSO group (DMSO: 3.70 ± 2.4 cm3) or PBS group cells (PBS: 3.78 ± 2.20 cm3, ANOVA P < 0.01). (C) Tumor weight of the treatment experiment. YM155 treatment decreased weight of tumors (YM155 5 mg/kg: 1.05 ± 0.24 g; YM155 10 mg/kg: 0.72 ± 0.17 g) compared to DMSO group (DMSO: 2.06 ± 0.38 g) or PBS group cells (PBS: 2.36 ± 0.43 g, ANOVA P < 0.01). (D) Body weight of nude mice in the treatment experiment. Body weight of nude mice treated with YM155 was almost same with control group (YM155 5 mg/kg:20.12 ± 1.66 g; YM155 10 mg/kg: 19.92 ± 1.72 g) compared to DMSO group (DMSO: 20.88 ± 1.83 g) or PBS group cells (PBS: 20.66 ± 1.37 g, ANOVA P >0.05).