Activated CAFs are known to support tumor growth and secrete chemokines and cytokines like TGFβ, vascular endothelial growth factor-A (VEGF-A), other angiogenic factors, prostaglandin-2 (PGE2), and indolamine-2,3-dioxygenase (IDO) to promote immunosuppression, where the latter is known to be secreted by inflammatory CAFs [6,9,40,42,43]. The gene discussed is IDO1; the disease is neoplasm.