Finally, we could not show in vivo data supporting the hypothesis of this study; that is, there were no characteristic findings on histological examinations of both tumours developed after the injection of PC3 cells into the SV and the prostate, such as those suggesting different metastatic potentials, and both tumours were shown to exhibit strong uPA expression by immunohistochemical staining (data not shown), which may be due to the originally high expression level of uPA in PC3 cells, resulting in the lack of evident difference in uPA expression between tumours in the SV and the prostate. This evidence concerns the gene PLAU and neoplasm.