PDGFRL (platelet-derived growth factor receptor-like) is a multifunctional protein with context-dependent roles across diverse pathological conditions. Primary function: PDGFRL exhibits platelet-derived growth factor beta-receptor activity and platelet-activating factor receptor activity 1. Mechanism: PDGFRL operates through distinct signaling pathways depending on tissue context. In cardiac fibrosis, PDGFRL functions downstream of GLIPR2 via the AKT/mTOR pathway to promote endothelium-mesenchymal transition 2. In hepatocellular carcinoma, PDGFRL acts as a tumor suppressor by inhibiting STAT3 pathway activation 3, whereas in colorectal cancer, recombinant PDGFRL protein inhibits proliferation and induces G0/G1 cell cycle arrest 4. Disease relevance: PDGFRL is associated with colorectal cancer, endometriosis, osteoarthritis, acute myocardial infarction-related cardiac fibrosis, hepatocellular carcinoma, COVID-19 severity, Behçet disease, and exercise-induced immunosuppression 15234678. In osteoarthritis, PDGFRL is upregulated in degenerative cartilage and promotes chondrocyte apoptosis and ECM degradation 5. Clinical significance: Anti-PDGFRL antibody treatment demonstrates therapeutic potential in osteoarthritis by suppressing cartilage degeneration 5. PDGFRL represents a novel biomarker for endometriosis diagnosis and a therapeutic target in multiple disease contexts.