FBXO32 and sarcopenia: Knock-out mice lacking these E3 ligases are protected from muscle atrophy.21 C2C12 muscle cells treated with 5 mM leucine have demonstrated suppressed MAFbx/atrogin-1 and MuRF1 mRNA levels.22 Therefore, leucine supplementation to older adults may serve as a potential strategy to combat the progression of sarcopenia.