104, 105, 106 VPC were injected into nude mice bearing KP-1N xenograft (n=10 for each group). (A) Tumor volume (left panel) and weight (right panel) of KP-1N xenografts with or without VPC transplantation (* P < 0.05, versus control mice; PBS injected). (B) Growth of KP-1N xenografts with or without VPC transplantation was observed for up to 6 weeks (PBS, 105 or 106 VPC injected; n=6 for each). Mice were humanely killed following development of a tumor larger than 2,000 mm3 or a tumor harboring an ulcer.