FBXO32 and neoplasm: Both atrogin-1 and MuRF-1 are E3 ubiquitin ligases expressed in skeletal muscle which target proteins for proteolysis[39, 40].We found increased intramuscular levels of atrogin-1 (Fig 3A) and MuRF-1 (Fig 3B) in the tumor-bearing mice by qPCR.