CD248 (endosialin/TEM1) is a type I transmembrane glycoprotein primarily expressed on activated mesenchymal cells, including cancer-associated fibroblasts and pericytes 1. The protein plays critical roles in promoting pathological processes across multiple diseases. In fibrotic conditions, CD248 promotes tissue scarring by stabilizing TGF-β receptors and enhancing TGF-β signaling in dermal fibroblasts, leading to increased extracellular matrix production 2. In diabetic kidney disease, CD248 induces maladaptive unfolded protein response by inhibiting IRE1α-mediated XBP1 splicing through formation of a multiprotein complex 3. In cancer, CD248 functions through multiple mechanisms: it promotes angiogenesis and tumor growth in lung cancer by derepressing Wnt/β-catenin signaling in pericytes, leading to increased expression of angiogenic factors OPN and SERPINE1 4. Additionally, CD248-positive cancer-associated fibroblasts suppress CD8+ T cell infiltration by inhibiting STAT1 phosphorylation and reducing CXCL9/10 chemokine expression 5. The protein shows minimal expression in normal adult tissues but is highly upregulated in pathological conditions, making it an attractive therapeutic target for cancer, fibrosis, and other diseases involving activated mesenchymal cells 16.