Consistent with the proangiogenic activation of spheroid-growing CT26 cancer cells, both endothelial cell (as CD31-expressing cells) and alpha-smooth muscle actin (SMA)-expressing cell numbers significantly (p < 0.01) increased in metastatic nodules produced by 3D-cultured CT26 cells as compared to those developed by monolayer-cultured CT26 cells (Figures 5C–F). This evidence concerns the gene PECAM1 and cancer.