An immunohistochemical staining with anti-murine CD31 antibody revealed a significantly decreased microvessel density in the IFN-α gene-transduced AsPC-1 subcutaneous tumour models (Figure 7); 10 representative fields under a microscope showed 121, 13 and 44 microvessel counts for the tumours injected with AdCA-AP, AxCA-IFN and AdCA-mIFN, respectively. This evidence concerns the gene PECAM1 and neoplasm.