FBXO32 and Cachexia: However, recent data suggest that the ubiquitin-protein ligases (E3), muscle ring-finger 1 (MURF1); (Bodine et al, 2001) and muscle atrophy F box (MAFbx)/atrogin-1 (Gomes et al, 2001), may be the rate-limiting step in various conditions of muscle atrophy including cachexia.