A total of 3842 endothelial cells from seven tumor samples and one paracancerous tissue were obtained from the GEO database, based on the marker genes VWF, CDH5, RAMP2 and CLDN5 (Figure 1a),26, 27 of which 3724 and 118 cells were derived from cancer tissues and paracancerous tissue, respectively. Here, CLDN5 is linked to cancer.