FGF21 and mitochondrial disease: While FGF21 is known to regulate cell proliferation, development, pyroptosis, apoptosis, autophagy, and mitochondrial diseases (Chen et al., 2020; Gomez-Samano et al., 2017; Salminen et al., 2017; Wu et al., 2021), few studies have investigated its role in regulating mitochondrial dysfunction and ferroptosis in PNI.