TRIM63 and cancer: Muscle atrophy F-box (MAFbx/Atrogin-1), Muscle RING-finger protein-1 (MuRF1/TRIM63), neural precursor cell-expressed developmentally downregulated gene 4.1 (Nedd4.1), TNF-associated factor 6 (TRAF6), muscle ubiquitin ligase of SCF complex in atrophy-1 (MUSA), and recently discovered Specific of Muscle Atrophy and Regulated by Transcription (SMART) are specific E3 ubiquitin ligases that have been found to be persistently up-regulated in different models of cancer cachexia [14,15,16].