TRIM63 and cancer: In particular, the expression of well characterized muscle-specific ubiquitin ligases, namely atrogin-1/MAFbx, MuRF1/TRIM63 and, more recently, MUSA 1 and SMART [7,9,10,11,12] increases rapidly upon a variety of stressors, such as GC and pro-inflammatory cytokines [4,10], cancer cachexia and other pathological states [4,5].