Markers expressed by cells sharing some lineage with CAFs, but not expressed by CAFs, were absent from most cells isolated from GBM by serial trypsinization, including EPCAM, an epithelial cell marker expressed by 0.07% of the cells, SMTN, a smooth muscle cell marker expressed by 4% of the cells, and PECAM1, an endothelial marker expressed by 10.7% of the cells. The gene discussed is PECAM1; the disease is glioblastoma.