PECAM1 and cancer: Flow cytometry analysis (Supplementary Fig. 1A), immunostaining (Supplementary Fig. 1B), and western blotting (Supplementary Fig. 1C) experiments showed that the fibroblasts expressed α-SMA, FAP, but did not express endothelial cell marker CD31, immune cell marker CD45, or epithelial cell marker CK19, demonstrating that the fibroblasts were highly purified, and thus could be used as cancer-associated fibroblast (CAF) and normal fibroblast (NF) cell lines in subsequent experiments.