FGF9 is a fibroblast growth factor that regulates cell proliferation, differentiation, and migration through FGFR signaling 1. It activates downstream pathways including ERK1/2-GSK-3β and Wnt signaling to modulate target gene expression 23. In hepatic pathology, FGF9 promotes nonalcoholic steatohepatitis (NASH)-driven hepatocellular carcinoma by recruiting β-catenin to increase extracellular matrix synthesis; FGF9 knockdown reduces tumor burden in NASH models 2. In prostate cancer, cancer-associated fibroblasts secrete FGF9 in response to TNF-α, activating FGFR1 signaling to promote PTEN-deficient tumor growth 4. FGF9 also mediates chemotherapy resistance: in ovarian cancer, circITGB6 stabilizes FGF9 mRNA to promote M2 macrophage polarization and cisplatin resistance 5, while in non-small cell lung cancer, the miR-582-5p/FGF9 axis activates Wnt pathways to drive gemcitabine resistance 3. Regarding orthopedic diseases, FGF9 regulates cartilage metabolism and is implicated in osteoarthritis and intervertebral disc degeneration pathogenesis 1. In diabetic nephropathy, FGF9 is a hub gene associated with renal fibrosis and metabolic reprogramming 6. Clinically, FGF9 mutations cause Multiple synostoses syndrome 3. These findings identify FGF9 as a therapeutic target across multiple cancer types and degenerative diseases.