FOXO3 and sarcopenia: In the skeletal muscle of senescence-accelerated mouse (SAM) prone 8 (SAMP8), a canonical sarcopenia model, protein synthesis-related markers (Akt, mTOR and p70S6K) were reduced; however, the protein degradation-associated markers (FoxO3, MuRF-1 and MAFbx) were elevated indicating during advancing process of aging, protein turnover has a pro-degradation trend that leads to muscle atrophy which contributes to the occurrence of sarcopenia [55].