FGF21 and lung cancer: Another myokine, myostatin (MSTN), can cause muscle atrophy, but plasma Mstn concentrations negatively correlate with the development of the cachexia phenotype in colorectal or lung cancer patients.136 Consistently, patients with cachexia presented the highest FGF21 levels.137 Fu et al. revealed that ablation of FUNDC1 in skeletal muscle, a mitophagy mediator, promotes adipose tissue thermogenesis by increasing FGF21 levels,138 suggesting that FGF21-mediated energy metabolism modulates muscle‒adipose interactions.