A. PBS/atelocollagen complex, nonsense siRNA/atelocollagen complex, or PLK-1 siRNA/atelocollagen complex was administered by intravenous injection. Representative mice showing bioluminescence after siRNA treatment. The photon counts of each mouse are indicated by the pseudocolor scales. B. Growth curves of inoculated Luc-labeled A549 cells measured by the IVIS (pink square, nonsense siRNA/atelocollagen complex (25 μg siRNA)-treated mice; blue diamond, PBS/atelocollagen complex-treated mice; orange triangle, PLK-1 siRNA/atelocollagen complex (25 μg siRNA)-treated mice; n = 5 for each group. On day 35 after inoculation, the luminesecence in the PLK-1 siRNA/atelocollagen-treated mice was significantly suppressed compared with that in other groups. * p < 0.05. Mean ± SD. C. Macroscopic analysis of mice livers after day 70 of inoculation. White nodules are metastatic liver tumors. Treatment with PLK-1 siRNA (25 μg) remarkably inhibited the growth of liver metastases compared with PBS or nonsense siRNA treatments (25 μg).