Increased In Vivo Tumor-restoration and Proliferative Ability in LC-CD133 + We further evaluated the in vivo tumor-restoration and proliferative ability of LC-CD133 + and LC-CD133 2 by xenotransplanted tumorigenicity analysis (Fig. 3A) . Four weeks after 10 4 cells were injected into the tail veins of SCID mice, a significant increase in the multiple nodules of tumor formation on lung surface was noted in the LC-CD133 + -injected group (Figs. 3A4 & 3A7) but not in the LC-CD133 2 group (Fig. 3A1) . Diffuse infiltrations of LC-CD133 + from the lung parenchyma to the alveolar cavity were observed (Figs. 3A5, 3A6, and 3A8) . The histological examination demonstrated that the prominent neovascularization and thrombus formation were detected in the pulmonary parenchyma of LC-CD133 + -injected SCID mice (Fig. 3A9) . In contrast, no significant tumor foci or neovascular formation was found in the lungs of LC-CD133 2 -injected SCID mice (Figs. 3A2 & 3A3) . We further investigated the in vivo tumor growth rate in 10 4 LC-CD133 + cells, 10 6 LC-CD133 2 cells, and 5610 6 parent tumor cells from the same patient. The finding demonstrated that the tumor growth rate of the 10 4 LC-CD133 + group (from Patients No. 1, 2, 4, and 7; Table 1 ) was significantly higher than that of the 10 6 LC-CD133 2 group and 5610 6 parental tumor cell group (Fig. 3B) . Furthermore, 10 4 LC-CD133 + isolated from secondary tumors can further generate new (second) tumors from transplanted SCID mice. Results of flow cytometry showed that a high percentage (60%) of CD133-positive cells was detected in the second tumor (Fig. 3C ). In addition, one thousand LC-CD133 + isolated from the second tumor can also generate a new (third) tumor in transplanted SCID mice (Fig. 3C) . To sum, our data indicated that LC-CD133 + present self-renewing and repopulation capabilities both in vitro and in vivo.