PECAM1 and neoplasm: Quantitative analysis indicated that the level of MT1-MMP in PECAM-1-positive blood vessels did not significantly differ between control and HSA/TIMP-2-treated tumors (P = 0.918), which was confirmed by western blotting of tumor lysates from the HSA/TIMP-2-treated group (Fig. S3C, D; P = 0.096).