TRIM63 and muscle atrophy: On the other hand, phosphorylated Akt inhibits protein degradation through inhibition of Muscle RING finger 1 (MuRF1) and muscle atrophy F-box (MAFbx/Atrogin-1), which are muscle-specific E3 ubiquitin ligases mediated by forkhead box O3a (FoxO3a) [62].