Pan-cancer-associated fibroblasts (PanCAFs), marked by ACTA2, COL1A1, COL1A2, COL3A1, CIR, CIS, PDPN, PDGFRB, and SERPINF1 expression (19–21, 23, 25), represent a conserved population driving tumor progression through ECM remodeling, stromal signaling, and immune evasion across diverse malignancies. The gene discussed is COL3A1; the disease is cancer.