FGF21 and retinal disorder: To determine if lipid metabolism is key in FGF21 promotion of retinal vessel growth in Phase I retinopathy mice, FGF21 (PF-05231023, 0.5 mg/kg) was co-injected with etomoxir (4 mg/kg), the inhibitor of mitochondrial lipid transporter CPT1A to block fatty acid oxidation [46], from P7 to P9.