Comparing CD31-positive staining between tumors formed by instilling tumor cells alone and tumor cells plus HK cells, BlCaPt15 cell primary tumor angiogenesis was significantly enhanced in the presence of HK cells as indicated by digital analysis of the percentages of vasculature covered tumor areas, (Figure 3, dark brown staining, P = 0.0009). This evidence concerns the gene PECAM1 and neoplasm.