Fig. 2.

Fibroblast growth factors (FGFs) 8, 9, 18, and 23 in osteoarthritis (OA). FGF8 and FGF23 activate the Wnt/β-catenin pathway; FGF9 and FGF18 activate the PI3K-Akt pathway; FGF18 and FGF23 activate the Ras-MAPK pathway. The effects of each FGF-activating downstream signaling pathway on articular chondrocytes are shown. Dvl dishevelled, Axin axis inhibition, CK1 casein kinases 1, HS heparan sulfates, FRS2α FGFR substrates 2α, SOS son of sevenless, GRB guanine nucleotide exchange factor, GAB GRB2-associated binding protein, PKC protein kinase C, JNK c-Jun N-terminal kinase, MEK mitogen-activated extracellular signal-regulated kinase, MAPK mitogen-activated protein kinase, PI3K phosphoinositide 3-kinase, Akt protein kinase B